Chapter 2 Experiment

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Microscale ChemistryExperiments:Adaptation to

Malaysian National

Curriculum

School of Chemical Sciences

Universiti Sains MalaysiaPenang, Malaysia

Prepared under UNESCO Contract No: 4500049693



2

CONTENTS

Foreword 6

Preface 8

List of apparatus 9

CHAPTER 1

INTRODUCTION TO CHEMISTRY

SCIENTIFIC METHOD

A. Investigating the effect of the temperature of water on the solubility of sugar 10

CHAPTER 2

THE STRUCTURE OF THE ATOM

A. DIFFUSION OF PARTICLES IN SOLIDS, LIQUIDS AND GASES

I. Diffusion of gases 12

II. Diffusion of liquids ** 13

III. Diffusion of solids 13

CHAPTER 3

CHEMICAL FORMULAE AND EQUATIONS

A . DETERMINING THE EMPIRICAL FORMULA OF COPPER(II) 15

OXIDE **

B . CONSTRUCTING BALANCED CHEMICAL EQUATIONS

I. Heating of copper(II) carbonate ** 18

II. Formation of ammonium chloride 19

III. Precipitation of lead(II) iodide 19

CHAPTER 4

PERIODIC TABLE OF ELEMENTS

A . INVESTIGATING THE CHEMICAL PROPERTIES OF GROUP 17

ELEMENTSI. Reactions of halogens with water 21

a) Chlorine with water **

b) Bromine with water ** c) Iodine with water



3

II. Reactions of halogen with iron 23a) Chlorine with iron **

b) Bromine with iron **

c) Iodine with iron **

III. Reactions of halogens with sodium hydroxide, NaOH solution 25a) Chlorine with sodium hydroxide, NaOH solution

b) Bromine with sodium hydroxide, NaOH solution.

c) Iodine with sodium hydroxide, NaOH solution

B . STUDYING THE PROPERTIES OF OXIDES OF THE ELEMENTS IN

PERIOD 3I. Reaction of oxides of Period 3 elements with water 29

II. Reaction of oxides of Period 3 elements with 2 M nitric acid and 30

2 M sodium hydroxide solutions

CHAPTER 5

CHEMICAL BONDS

A . PREPARATION OF IONIC COMPOUNDS

I. Preparation of magnesium oxide 32

II. Preparation of iron(III) chloride ** 33

B . COMPARING THE PROPERTIES OF IONIC AND COVALENT COMPOUNDSI. Melting point and boiling point 35

II. Solubility in water and organic solvents 36

III.Electrical conductivity 37

CHAPTER 6

ELECTROCHEMISTRY

A .CLASSIFYING CHEMICALS INTO ELECTROLYTES AND

NON-ELECTROLYTESI. Molten substances 39

II. Aqueous solutions 40

B . ELECTROLYSIS OF MOLTEN COMPOUNDS 42

C . INVESTIGATING THE ELECTROLYSIS OF AQUEOUS SOLUTIONS

I. Electrolysis of sodium hydroxide solution ** 44

II. Electrolysis of copper(II) sulphate solution 45

D . PURIFICATION OF COPPER 47



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E . ELECTROPLATING AN OBJECT WITH COPPER 49

F .PRODUCTION OF ELECTRICITY FROM CHEMICAL 51

REACTIONS IN A SIMPLE VOLTAIC CELL

G .PRODUCTION OF ELECTRICITY FROM CHEMICAL REACTIONS 53 IN A DANIEL CELL

H . CONSTRUCTING THE ELECTROCHEMICAL SERIES 55

USING THE PRINCIPLE OF DISPLACEMENT OF METALS

CHAPTER 7

ACID AND BASES

A . INVESTIGATING THE ROLE OF WATER IN SHOWING 57

THE PROPERTIES OF ACIDS

B . STUDYING THE CHEMICAL PROPERTIES OF ACIDSI. Reactions of acids with bases 59

II. Reactions of acids with metals 61III.Reactions of acids with metal carbonates 62

C . STUDYING THE CHEMICAL PROPERTIES OF BASES

I. Reactions of bases with acids 64II. Reactions of bases with ammonium salts 65

III.Reactions of bases with metal ions 65

D . MEASURING THE pH OF SOLUTIONS USED IN DAILY LIFE ** 67

E . DETERMINING THE END POINT OF THE TITRATION BETWEEN 69

HYDROCHLORIC ACID, HCl AND SODIUM HYDROXIDE, NaOH

SOLUTION USING AN ACID-BASE INDICATOR **

CHAPTER 8

SALTS

A. SOLUBILITY OF NITRATE, SULPHATE, CARBONATE AND 73

CHLORIDE SALTS

B . PREPARATION OF SOLUBLE SALTS BY MIXING ACIDS WITH BASES

I. To determine the volume of acid for neutralization 75II. Preparation of the salt 76

III.Recrystallisation of the salt. 76



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C. PREPARATION OF SOLUBLE SALTS BY MIXING AN ACID 78

WITH AN INSOLUBLE METAL OXIDE

D. PREPARATION OF INSOLUBLE SALTS BY CARRYING OUT A

PRECIPITATION REACTION I. Preparation of lead(II) iodide 80

II. Preparation of lead(II) chromate(VI) 80

III.Preparation of barium sulphate 81

E .CONSTRUCTING THE IONIC EQUATION FOR THE 82

FORMATION OF LEAD(II) CHROMATE(VI)

F . CARRYING OUT CHEMICAL TESTS TO IDENTIFY GASESI. Test for oxygen gas, O2 84II. Test for hydrogen gas, H2 85

III. Test for carbon dioxide gas, CO2 86IV. Test for ammonia gas, NH3 86

V. Test for chlorine gas 87VI. Test for hydrogen chloride gas, HCl 87

VII.Test for sulphur dioxide gas, SO2 88

VIII.Test for nitrogen dioxide gas, NO2 89

G . STUDYING THE EFFECT OF HEAT ON CARBONATE AND NITRATE SALTSI. Carbonate salts ** 91

II. Nitrate salts 92

H . TESTING FOR THE PRESENCE OF ANIONS IN AQUEOUS SOLUTION I. Test for carbonate ion, CO3

2- 95

II. Test for chloride ion, Cl-

96III.Test for sulphate ion, SO4

2-96

IV.Test for nitrate ion, NO3-

97

CHAPTER 9

MANUFACTURED SUBSTANCES IN INDUSTRY

A. PREPARATION OF AMMONIUM SULPHATE FERTILIZER

I. To determine the volume of acid for neutralization 99II. Preparation of the salt 100

** Experiments from the UNESCO Advanced Teaching and Learning Packages on

Microchemistry Experiences which have been adapted to the Malaysian National

Curriculum (Form Four)

websitehttp://portal.unesco.org/science/en/ev.php-

URL_ID=6816&URL_DO=DO_TOPIC&URL_SECTION=201.html



6

FOREWORD

In Malaysia, Chemistry is offered to students at the upper secondary level beginning

in Form Four (equivalent to Grade 10). The chemistry curriculum is organised based

on the following themes: introduction to chemistry, matter around us, interactions

between chemicals and production and management of manufactured chemicals.

Central to the teaching-learning approach in the chemistry curriculum is practical work

which involves scientific investigations and hands-on activities. It also has the potentialto significantly enhance learning and development of conceptual understanding.

Microscale chemistry is an approach to performing chemistry experiments which provides hands-on activities and personal experiences where students can do experiments

individually. It is conducted by using reduced amounts of chemicals, miniature labware,

safe, easy manipulative techniques and high quality skills. Using this approach,experiments in this manual have been developed at the School of Chemical Sciences,Universiti Sains Malaysia (USM) according to the chemistry syllabus for the Malaysian

Form Four Integrated Curriculum for Secondary Schools (KBSM).

I hope that with this manual of experiments, teachers will be encouraged to view

microscale chemistry experiments as a viable alternative to conducting practical work in

chemistry. In this respect, I would like to acknowledge the authors, Prof. NoritaMohamed, Mrs Mashita Abdullah and Assoc. Prof. Zurida Hj Ismail for their dedication

in compiling this work.

USM, through its innovative effort is proud to collaborate with any party, UNESCO in particular, in advancing further the use of microscale chemistry.

Prof. Tan Sri Dato’ Dzulkifli Abdul Razak

VICE-CHANCELLOR

UNIVERSITI SAINS MALAYSIA

11800 USM, PENANG

MALAYSIA



7

The Global Microscience Experiments Project, created by UNESCO in close cooperationwith various international and national organisations, is very well known throughout the

world. Many teaching and learning materials on Microscience experiments covering

Primary Sciences, Chemistry, Biology and Physics have been prepared and are available

free on the UNESCO website. However, the key point for the successful development of the project in a national level is the preparation of adapted versions of the existing

materials to fit the national educational needs and curricula.

Malaysian specialists have prepared the adapted version of the chemistry materials using

part of UNESCO’s learning materials with great success: 39 new experiments were testedusing the advanced Microchemistry kits and 13 experiments were adapted from

UNESCO materials.

We hope that the present adapted version of the UNESCO learning materials in

microchemistry and especially the 39 new experiments could be examined by other

interested countries and could be used totally or partially in their own educational programs.

We would like to congratulate warmly our Malaysian colleagues for the present

publication and the excellent result which can constitute an example of best practicewithin the Global Microscience Experiments Project and a good model for use by other

countries in the world.

We believe that the Malaysian adaptation of Microchemistry Experiments contributes to

a new phase of the Global Microscience Experiments Project whereby such adaptations

become important components of the teaching and learning materials available to all.

Maria Liouliou

PROJECT COORDINATOR

UNESCO, NATURAL SCIENCES SECTOR

DIVISION OF BASIC AND ENGINEERING SCIENCES

Academician Alexandre Pokrovsky

DIRECTOR

MICROSCIENCE EXPERIMENTS PROGRAM OF

INTERNATIONAL ORGANISATION FOR CHEMICAL SCIENCES IN

DEVELOPMENT (IOCD)



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PREFACE

This manual of experiments has been prepared as a students’ learning package for Form

Four (equivalent to Grade 10) secondary school students. The experiments have been

designed using the Advanced Microchemistry Kit (Somerset Educational South Africa)

and also glassware with a smaller volume.

It comprises nine chapters which include: introduction to chemistry, the structure of the

atom, chemical formulae and equations, periodic table of elements, chemical bonds,electrochemistry, acids and bases, salts and manufactured substances in industry.

Thirteen experiments (marked with ** in the Table of Contents) in this manual have beenadapted from experiments in the ‘UNESCO Advanced Learning Package on

Microchemistry Experiences’ prepared by the RADMASTE UNESCO Associated Centre

of the University of Witwatersrand (South Africa) in cooperation with the Committee onTeaching of Chemistry of the International Union of Pure and Applied Chemistry

(IUPAC) and UNESCO. The rest of the experiments (39) have been developed

according to the Malaysian Form Four chemistry syllabus by replacing the traditionalapparatus with microscale chemistry apparatus. Our continuing work with microscale

chemistry experimentation with teachers and students through workshops held and school

trials, have shown that with this approach, there is a reduction of up to 70 percent in

chemical wastes produced and chemical costs, and a saving of up to 75 percent in timespent in conducting the experiments.

We hope that with these experiments, teachers will be able to experience themselves thefeasibility of conducting chemistry practical work with a microscale approach.

We would like to especially acknowledge the assistance of Academician Alexandre

Pokrovsky, Director of Microscience Experiments Programme IOCD and Prof. John D.Bradley, Director of RADMASTE Centre. We are also grateful to Prof. Wan Ahmad

Kamil Mahmood, Dean of the School of Chemical Sciences for his support in the

development of microchemistry experiments at Universiti Sains Malaysia.

Prof. Norita Mohamed ([email protected])

Mrs Mashita Abdullah ([email protected])

SCHOOL OF CHEMICAL SCIENCES

Assoc. Prof. Zurida Hj Ismail ([email protected])

SCHOOL OF EDUCATIONAL STUDIES

UNIVERSITI SAINS MALAYSIA

11800 USM, PENANG

MALAYSIA



9

List of apparatus

Advanced Microchemistry Kit (Somerset Educational)

Big sample vial and lid

ComboplateCombustion tube

Crossarms for microstandGas collecting tube

Glass fusion tube

Glass rod

LEDLid 1

Lid 2

Microburner Microburette

MicrospatulaMicrostandPlasticine

Propette

Silicone tubeSmall sample vial and lid

Straw electrodes

Syringe

Voltmeter Wire connections

Other components

10 cm3

beaker

25 cm3

conical flask 10 cm

3measuring cylinder

Blue litmus paper

Battery 9V

Durham tubesFilter funnel

Microcrucible

Microtripod stand

Pencil leadPipe-clay triangle

Small wire gauzeTest tube

Thermometer Universal indicator paper

W-tube

Wire gauze



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Chapter 1: Introduction to Chemistry

Scientific Method

A. Investigating the effect of the temperature of water on the solubility of sugar

Objective: To investigate the effect of the temperature of water on the solubility of

sugar

Apparatus: 10 cm3

measuring cylinder, 10 cm3

beakers, electronic balance, microburner,

microtripod stand, wire gauze, glass rod, thermometer.

Materials: Sugar and water.

Figure 1.1

Procedure:

1. Fill a measuring cylinder with 10 cm3

of water and pour it into a 10 cm3

beaker.2. Record the temperature of the water with a thermometer.

3. Fill another 10 cm3

beaker with sugar. Weigh the beaker and its contents and

record the weight as a g.

4. Add the sugar a little at a time to the 10 cm3

of water in the beaker using amicrospatula.

5. Continue adding the sugar until no more sugar dissolves in the water.

6. Weigh the beaker with the sugar again and record the weight as b g.7. The amount of sugar that dissolves in the water at room temperature is (b-a) g.

8. Repeat the experiment using water heated to different temperatures – 40 °C,

50 °C, 60 °C and 70 °C each time. Heat the water using a microburner (refer tosetting up of the microburner below).

9. Record the results in the following table.



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Setting up the microburner:

Fill three quarters of the microburner vial with methylated spirit. Attach the

microburner lid (with glass tube and wick) to the vial and light the microburner.

Data and Observations:

Temperature (°C)Room

temperature40 50 60 70

Initial mass of beaker and

Its contents (g) A b c d

Final mass of beaker and its

contents (g) B c d e

Mass of sugar dissolved (g) (b-a) (c-b) (d-c) (e-d) (f-e)

Conclusions:

Questions:

1. State the hypothesis for the experiment.

2. State:(i) the manipulated variable.

(ii) the responding variable.(iii) the fixed(controlled) variables of the experiment.

3. Plot a graph of the mass of sugar dissolved against temperature.

(Both axes must be labeled with their units and the title of the graph must begiven).

4. From the graph, give a conclusion for the experiment.

References:

1. Low, S.N., Lim, Y.C., Eng, N.H., Lim, E.W. & Ahmad, U.K. (2005). Chemistry

practical book form 4, Integrated Curriculum for Secondary Schools , Abadi Ilmu Sdn.

Bhd: Petaling Jaya.

2. Loh, W.L. & Tan, O.T. (2006). Exploring Chemistry Form 4. Fajar Bakti Sdn. Bhd:Shah Alam.



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Chapter 2: The Structure of the Atom

A. Diffusion of particles in solids, liquids and gases

Objective: To investigate the diffusion of particles in a gas, a liquid and a solid.

Apparatus: Gas collecting tube, comboplate, small sample vial and lid, big sample vial

and lid, syringe, silicone tube, propette and plasticine.

Materials: Liquid bromine, Br 2, 1 mol dm-3

potassium manganate(VII), KMnO4

solution, potassium manganate(VII), KMnO4 crystals, hot liquid gel, tap water.

Procedure:

I. Diffusion of gases

Figure 2.1

1. Put a gas collecting tube in well F1 of the comboplate in a vertical position using

plasticine at the bottom of the well.2. Take the comboplate into the fume chamber.

3. Use a clean, dry propette to add 2-3 drops of bromine into the tube.

4. Close the tube immediately and record any observations for several minutes.

Watch Out! Liquid bromine, Br2 is toxic and corrosive. Wear gloves when

handling this substance. This activity must be carried out in a fume chamber.



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II. Diffusion of liquids

Figure 2.2

1. Fill ¾ of a small sample vial with water.

2. Fill the syringe with 1 mol dm-3

of KMnO4 solution.

3. Attach the silicone tube to the nozzle of the syringe.

4. Carefully insert the silicone tube into the water in the vial until the open endtouches the bottom.

5. Press the plunger of the syringe slowly so that the KMnO4 solution flows down

the tube into the water at the bottom of the vial.

6. Carefully remove the tube and syringe.7. Put a lid onto the vial and seal the hole in the lid with a piece of plasticine.

III. Diffusion of solids

Figure 2.3



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1. Fill a big sample vial with the hot gel solution and leave it aside to solidify.

2. Put some crystals of KMnO4 on the lid of the vial and close the vial containing thegel. Put the vial upside down as shown in Figure 2.3.

3. Leave the vial for one day and record any changes which have occurred.


Experiments Observations

I

II

III

Conclusions:

Questions:

1. Why must the test tube in Section III be clamped upside down?

2. Based on your observations in Sections I, II and III, what can you conclude?

3. Based on your observations, arrange the rate of diffusion in a gas, a liquid and asolid in ascending order. Explain your answer.

4. Based on your results, define diffusion.

5. In Section I, what will happen if you replace bromine, Br 2 with a lighter gas such

as chlorine, Cl2?6. What will you observe if you repeat the activity in Section II with boiling water?

References:

1. Low, S.N., Lim, Y.C., Eng, N.H., Lim, E.W. & Ahmad, U.K. & Tan, L. L. (2005).Chemistry practical book form 4, Abadi Ilmu Sdn.Bhd: Petaling Jaya.

2. Bell, B. & Bradley, J.D. (2002). Advanced learning packages, Microchemistry

experiences, Magister-Press Publishing House: Moscow.



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Chapter 3: Chemical Formulae and Equations

A. Determining the empirical formula of copper(II) oxide

Objective: To determine the empirical formula of copper(II) oxide

Apparatus: Comboplate, 2 cm3

syringes, glass tube (6 cm x 4 mm), lid 1, lid 2,

microspatula, propette, 2 silicone tubes (4 cm x 4 mm), microburner and

matches.

Materials: 2 mol dm-3

sulphuric acid, H2SO4, granulated zinc, Zn, 1 mol dm-3

copper(II) sulphate, CuSO4 solution, copper(II) oxide, CuO powder, andmethylated spirit.

Figure 3.1Procedure:

1. Use a microspatula to add about 0.5 to 1 g of granulated zinc to well F1.

2. Fill two thirds of well F6 with tap water from a propette.3. Seal well F1 with lid 1. Seal well F6 with lid 2 so that the vent hole faces

outwards.

4. Connect one end of a silicone tube to the tube connector on lid 1. Connect oneend of the other silicone tube to the tube connector on lid 2.

5. Weigh the glass tube and record the weight.

6. Hold the glass tube in a horizontal position. Use the narrow end of a cleanmicrospatula to place a small quantity of copper(II) oxide powder in the center

of the glass tube.

7. Weigh the glass tube with the copper(II) oxide and record its weight.

8. Keep the glass tube horizontal and attach one end to the silicone tube on lid 1.Connect the other end to the silicone tube on lid 2. Note: keep the glass tube

horizontal at all times otherwise the powder might spill into well F1 or F6.



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9. Fill the syringe with 1 ml of 2 mol dm-3

sulphuric acid. Fit the nozzle of the

syringe into the syringe inlet on lid 1.

Watch Out! Be careful when you handle acids. Acids are corrosive.

10. Light the microburner (refer to pg 11, Chap 1) and place it away from thecomboplate.

11. Add the sulphuric acid very slowly from the syringe into well F1.

12. Using a propette, add slowly through the tube connector, 2 – 3 drops of copper(II) sulphate solution into well F1.

13. When a few bubbles have come through the water in well F6, bring the flame of

the microburner to the middle of the glass tube where the copper(II) oxide powder has been placed. Hold the microburner in this position.

Caution: Do not bring the flame of the microburner near the silicone tubes

(as they will melt) or the vent of well F1 (as hydrogen is explosive)

14. Stop heating the copper(II) oxide powder after about 2 minutes or after it has

changed in appearance. Blow out the microburner flame.15. Continue the flow of hydrogen gas, H2, until the apparatus cools down to room

temperature.

16. Weigh the glass tube and its content and record the weight.17. If there is water being sucked up from well F6 into the glass tube, disconnect

lid 2 from well F6.

18. Repeat heating, cooling and weighing in steps 13 to 16 until a constant mass isachieved. Record the constant mass in your notebook.

Caution: A mixture of hydrogen and air will explode when lighted.

Note: The 2 mol dm-3

sulphuric acid, granulated zinc and 1 mol dm-3

copper(II)sulphate solution can be replaced by 5.5 mol dm

-3hydrochloric acid and zinc

powder.


Description Mass (g)

Glass tube

Glass tube + copper(II) oxide

Glass tube + copper Copper

Oxygen

Moles

Moles of copper

Moles of oxygen

Mole ratio



17

Conclusions:

Questions:

1. Describe what happens to the CuO(s).2. What other changes occur in the glass tube?

3. What chemical reaction has occurred in the tube? Write down the chemical

reaction for the production of hydrogen.4. Why do you need to repeat heating, cooling and weighing until a constant mass is

achieved?5. Based on your results, calculate the empirical formula of copper(II) oxide.

References:

1. Low, S.N., Lim, Y.C., Eng, N.H., Lim, E.W. & Ahmad, U.K. & Tan, L.L. (2005).Chemistry practical book form 4, Abadi Ilmu Sdn. Bhd: Petaling Jaya.





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Chapter 3: Chemical Formulae and Equations

B. Constructing balanced chemical equations

Objective: To construct balanced chemical equations

Apparatus: Comboplate, glass fusion tube, silicone tube, crossarms for microstand,

microspatula, propettes, lid 2, microburner, W-tube.

Materials: Copper(II) carbonate, CuCO3 powder, lime water, Ca(OH)2, concentrated

hydrochloric acid, HCl, concentrated ammonia, NH3 solution, lead(II)

nitrate, Pb(NO3)2 solution and potassium iodide, KI solution.

Procedure:

I. Heating of copper(II) carbonate

Figure 3.2

1. Hold the fusion tube in a horizontal position. Use the narrow end of a plastic

microspatula to fill about ½ of the fusion tube with copper(II) carbonate powder. Note its color.

2. Set up the apparatus as shown in Figure 3.2 (refer to pg 11, Chap 1 for setting upof microburner).

3. Heat the copper(II) carbonate and pass the gas produced through limewater in

well F4. Observe what happens to the copper(II) carbonate and the limewater.4. When the reaction is completed, withdraw the silicone tube.

5. Record the observations in the notebook.



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II. Formation of ammonium chloride

Figure 3.3

1. Using a propette, place three or four drops of concentrated hydrochloric acid in

one of the outer tubes of the W-tube.2. Using another propette, place three or four drops of concentrated ammonia

solution into the other outer tube of the W-tube.

3. Shake the W-tube carefully to allow the gases to flow.

Caution: Do not shake vigorously. It may cause the solutions to mix together.

4. Observe what happens in the middle of the W-tube and record your observations.

Caution: Concentrated hydrochloric acid and ammonia are corrosive and

harmful. Therefore, handle these solutions carefully and carry out

these activities in the fume chamber.

III. Precipitation of lead(II) iodide

Figure 3.4



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1. Using a propette, place the lead(II) nitrate solution until ¼ of well F1 of the

comboplate is filled up.2. Add the potassium iodide solution until half of the well is filled up.

3. Stir the mixture using a microspatula and observe what happens.

4. Record your observations in your notebook.


Section Reactants Products

I

II

III

Conclusions:

Questions:

1. Construct a table to fill in the following data.a) The reactants and products in Sections I, II and III.

b) The state of each reactant and product that is whether it exists as a solid,

liquid, gas or aqueous solution.c) The chemical formula of each of the reactants and products.

2. Write a balanced chemical equation for each reaction that occurs.

References:




3. Gupta, H.O. (2007). A novel W-Tube for microscale experiments in chemistry. Journal of Chemical Education, 84(2), 321.



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Chapter 4: Periodic table of elements

A. Investigating the chemical properties of group 17 elements.

Objective: To investigate the chemical properties of group 17 elements.

I. Reactions of halogens with water

Apparatus: Comboplate, syringe, silicone tube, lid 1, lid 2, propette, microspatula, blue litmus paper.


hydrochloric acid, HCl, household bleach, potassium bromide,KBr solution, potassium manganate(VII), KMnO4, iodine, I2 solid,

distilled water.

Caution: Chlorine gas, bromine gas and solid iodine are poisonous. Carry out the

experiment in the fume chamber. Wear gloves and safety goggles whenhandling these halogens.

Procedure:

a) Chlorine with water

Figure 4.1

1. Pass the chlorine gas into 1 cm3

of distilled water in well F2, as shown in Figure

4.1.

2. Put a piece of blue litmus paper into the solution produced in well F2.3. Observe any changes in colour.

4. Record the observations in a table in your notebook.



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II. Reactions of halogens with iron

Apparatus: Comboplate, syringe, silicone tube, glass tube, propette, fusion tube,

crossarms microstand, microburner, plasticine.

Materials: 2 mol dm

-3

hydrochloric acid, HCl, household bleach, iron, Fe powder, potassium bromide, KBr, potassium manganate(VII), KMnO4, solid

iodine, I2, hot water, soda lime.

Procedure:

a) Chlorine with iron

Figure 4.4

1. Set up the apparatus as shown in Figure 4.4.

2. Heat the iron powder in the glass tube strongly with a microburner (refer to pg 11,

Chap 1 for setting up of microburner).

3. When the iron powder becomes red hot, add the 1.0 cm3

of hydrochloric acid veryslowly using the syringe, so that the chlorine gas produced will pass over the hot

iron powder.

4. Observe any changes. Record the observations in a table in your notebook.



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b) Bromine with iron

Figure 4.5


2. Heat the iron powder in the combustion tube strongly.

3. When the iron powder becomes red hot, add the potassium manganate(VII)solution very slowly, so that the bromine gas produced will pass over the hot iron

powder.

4. Observe any changes. Record your observations in a table in your notebook.

c) Iodine with iron

Figure 4.6



25

1. Put some iodine in a fusion tube and set up the apparatus as shown in Figure 4.6.

2. Heat the iron powder in the glass tube strongly.3. When the iron powder becomes red hot, heat the iodine crystals in the fusion tube

to sublime it.

4. Pass the iodine vapor over the hot iron powder until no further changes occur.

5. Record your observations in a table in your notebook.

III. Reactions of halogens with sodium hydroxide, NaOH solution

Apparatus: Comboplate, syringe, silicone tube, lid 1, lid 2, propette, microspatula.


hydrochloric acid, HCl, household bleach, potassium bromide,

KBr, potassium manganate(VII), KMnO4, iodine, I2 solid, 2 mol dm-3

sodium

hydroxide, NaOH solution.

Procedure:a) Chlorine with sodium hydroxide, NaOH solution

Figure 4.7

1. Pass the chlorine gas into 1 cm3

of sodium hydroxide solution in well F2, asshown in Figure 4.7.

2. Observe any changes in colour. Record your observations in your notebook.

Caution: Be careful when handling halogens and sodium hydroxide solution.



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b) Bromine with sodium hydroxide, NaOH solution.

Figure 4.8

1. Pass the bromine gas into 1 cm3

of sodium hydroxide solution in well F3 as

shown in Figure 4.8.2. Observe any changes in colour. Record your observations in your notebook.

c) Iodine with sodium hydroxide, NaOH solution

Figure 4.9

1. Put a small piece of solid iodine, I2 into 1 cm3

of sodium hydroxide solution in

well F4.

2. Stir the mixture using a microspatula until no further changes occur.



27

3. Observe any changes in colour.

4. Record your observations in a table in your notebook.


ObservationHalogen

Reactant Chlorine Bromine Iodine

Water

Iron powder

Sodium hydroxide

Construct a hypothesis for the experiment involving halogens and sodium hydroxide.

State the variables and the operational definition.

Conclusions:

Questions:

1. In Section I,

a) State the properties exhibited by each halogen when they react with water. b) What are the products formed when chlorine, bromine and iodine react

with water?

c) Write the chemical equations for the reactions.

2. What is the function of soda lime in Section II?



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3. Why must the iron powder be heated first before these halogens are passed over it

in Section II?4. a) What are the products for the reactions between chlorine, bromine and iodine

with iron?

b) Write the chemical equations for these reactions.

5. a) What are the products when chlorine, bromine and iodine react with sodiumhydroxide, NaOH solution?

b) Write the chemical equations for these reactions.

6. Describe the changes in reactivity of Group 17 elements when going down thegroup. Explain your answers.

References:

1. Low, S.N., Lim, Y.C., Eng, N.H., Lim, E.W. & Ahmad, U.K. & Tan, L.L. (2005).

Chemistry practical book form 4, Abadi Ilmu Sdn. Bhd: Petaling Jaya.

2. Bell, B. & Bradley, J.D. (2002). Advanced learning packages, Microchemistryexperiences, Magister-Press Publishing House: Moscow.

3. Microscale gas chemistry: experiments with chlorine. Retrieved from:

http://mattson.creighton.edu/Microscale_Gas_Chemistry.html.



29

Chapter 4: Periodic table of elements

B. Studying the properties of oxides of the elements in Period 3.

Objective: To study the properties of the oxides of elements in Period 3.

Apparatus: Comboplate, microspatulas, propette, syringe, glass rod, microburner, and

2 cm3

syringe.

Chemicals: Sodium oxide, Na2O, magnesium oxide, MgO, aluminium oxide, Al2O3,

silicone(IV) oxide, SiO2, phosphorus pentoxide, P2O5, universal indicator

solution, 2 mol dm-3

nitric acid, HNO3, and 2 mol dm-3

sodium hydroxide, NaOH solution distilled water.

Procedure:

I. Reaction of oxides of Period 3 elements with water.

Figure 4.10

1. Use a clean propette to fill half of wells F1 to F5 with distilled water.2. Use the spooned ends of different microspatulas to add sodium oxide, magnesium

oxide, aluminium oxide, silicone dioxide, and phosphorus pentoxide to wells F1

to F5 respectively.3. Stir the solution using the microspatula and observe the solubility of the oxides.

4. Add one drop of universal indicator solution to each solution and record the pH of the solution.



30

II. Reaction of oxides of Period 3 elements with 2 M nitric acid and 2 M sodium

hydroxide solutions

Figure 4.11

1. Use the spooned end of a microspatula to place one level spatula of sodium oxide powder into wells F1 and E1 of the comboplate.

2. Fill the syringe with 0.5 cm3

of nitric acid and 0.5 cm3

of sodium hydroxide to the

contents in each well F1 and E1.3. Light the microburner (refer to pg 11, Chap 1) and fully heat one end of the glass

rod in the flame.

Caution: Do not keep the rod in the flame for a long period.

4. Heat the reaction mixture in F1 by stirring with the heated glass rod.

5. Rinse and dry the rod, and repeat the heating process a few times.

6. Repeat this process to the contents of E1.

7. Record the solubility of sodium oxide in the two solutions.8. Repeat the experiment with magnesium oxide, aluminium oxide, silicon(IV)

oxide and phosphorus(V) oxide respectively in wells F2 to F5 and E2 to E5.


Observations

I. Oxide Solubility in water pH values of solution Inference

Na2O

MgO

Al2O3

SiO2

P2O5



31

II.

Oxide Solubility in 2 mol dm-3

NaOH

Solubility in 2 mol dm-3

HNO3

Inference

Na2O

MgO

Al2O3

SiO2

P2O5

Conclusions:

Questions:

1. Why are nitric acid and sodium hydroxide solution used in this experiment?

2. Write the chemical equations for all the reactions of the oxides of Period 3

elements with water, if any.3. Write the chemical equations for the reactions of sodium hydroxide solution and

nitric acid with

a) Magnesium oxide, MgO, if any. b) Aluminium oxide, Al2O3, if any.

References:





32

Chapter 5: Chemical bonds

A. Preparation of ionic compounds

Objective: To prepare ionic compounds

I. Preparation of magnesium oxide

Apparatus: Microcrucible, microtripod stand, pipe-clay triangle, microburner.

Materials: Magnesium ribbon, sand paper and methylated spirit.

Procedure:

Figure 5.1

1. Obtain a 2 cm length of magnesium ribbon.

2. Use sand paper to remove the oxide layer on the surface of the magnesium ribbon.

3. Place the magnesium ribbon in a microcrucible as shown in Figure 5.1.

4. Heat the magnesium ribbon strongly with a microburner (refer to pg 11, Chap 1).5. Observe what happens to the magnesium ribbon. Record it in your notebook.



33

II. Preparation of iron(III) chloride

Apparatus: Comboplate, syringe, silicone tube, glass tube, propette and microburner.

Materials: Iron, Fe powder, household bleach, 2 mol dm-3

Hydrochloric acid, HCl

and sodium hydroxide, NaOH solution.

Figure 5.2

Procedure:

1. Setup the apparatus as shown in Figure 5.2.

2. Heat the iron powder in the glass tube strongly.3. When the iron powder becomes red hot, add the 1.0 cm

3of hydrochloric acid

using the syringe very slowly, so that the chlorine gas produced passes over the

hot iron powder.4. Observe any changes. Record your observations in a table in your notebook.

Watch Out! Chlorine gas is poisonous. Do not inhale the gas.


Experiment Observations

I

II



34

Conclusions:

Questions:

1. a) What are the products of all three reactions?

b) Give the chemical equations for the reactions.

References:





3. Microscale gas chemistry: experiments with chlorine. Retrieved from:http://mattson.creighton.edu/Microscale_Gas_Chemistry.html.



35

Chapter 5: Chemical bonds

B. Comparing the properties of ionic and covalent compounds

Objective: To compare the properties of ionic and covalent compounds

I. Melting point and boiling point

Apparatus: Comboplate, microspatula, propette.

Materials: Sodium chloride, NaCl, sodium sulphate, Na2SO4, diethyl ether, (C2H5)2O

and hexane, C6H14.

Procedure:

Figure 5.3

1. Use the spooned end of a microspatula to place one level spatula of sodium

chloride and sodium sulphate into wells F1 and F2 of the comboplate.2. Use the propette to place three drops of diethyl ether and hexane into wells F3 and

F4 respectively.3. Observe their physical states. Leave them aside for 5 minutes and then observe

what happens.4. Make inferences regarding their melting points and boiling points.



36


Compound Physical state After 5 minutes Inference

Sodium chloride

Sodium sulphate

Diethyl ether

Hexane

II. Solubility in water and organic solvents

Apparatus: Comboplate, Durham tubes, propette.

Materials: Sodium chloride, NaCl, sodium sulphate, Na2SO4, diethyl ether, (C2H5)2O,hexane, C6H14 and cyclohexane, C6H12.

Figure 5.4

Procedure:

1. Use a spooned end of a microspatula to place two leveled spatulas of sodium

chloride in a Durham tube. Add 10 drops of water into it. Shake and observewhether sodium chloride is soluble or not in water.2. Place the Durham tube slanting in well F1 of the comboplate.

3. Repeat steps 1 and 2 using cyclohexane as a solvent in place of water.4. Repeat steps 1 to 3 by using two leveled spatulas of sodium sulphate.

5. Repeat steps 1 to 3 by using 10 drops of diethyl ether.

6. Repeat steps 1 to 3 by using 10 drops of hexane.



37


Solubility

CompoundIn water In organic solvent

Sodium chloride

Sodium sulphate

Diethyl ether

Hexane

III. Electrical conductivity

Apparatus: Microcrucible, battery 9V, LED, pencil lead, carbon electrodes,

comboplate, microburner, microspatula, wire gauze and microtripod stand.

Materials: Solid lead(II) bromide, PbBr 2, glucose, C6H12O6, 1 mol dm-3

sodium

chloride solution, NaCl.

Figure 5.5 Figure 5.6

Procedure:

1. Fill a microcrucible with solid lead(II) bromide until it is half full.2. Set up the apparatus as shown in Figure 5.5 (refer to pg 11, Chap 1 for setting up

of microburner).

3. Observe whether the LED lights up or not.

4. Heat the solid lead(II) bromide until it melts.5. Observe again whether the bulb lights up or not.



38

6. Repeat steps 1 to 5 using glucose instead of lead(II) bromide.

7. Use the set-up of apparatus in Figure 5.6 to test the electrical conductivity of thesodium chloride solution.

Data and observations:

Compound State Observation Inference

Solid

Lead(II) bromideMolten

Solid

GlucoseMolten

SolidSodium chloride

Aqueous solution

Conclusions:

Questions:

1. What can you generalize about the melting point, boiling point, solubility andelectrical conductivity for both covalent and ionic compounds?

References:





39

Chapter 6: Electrochemistry

A. Classifying chemicals into electrolytes and non-electrolytes

Objective: To classify substances into electrolytes and non-electrolytes

Apparatus: 9V battery, pencil leads, LED, microcrucible, microburner, microtripod

stand, small wire gauze, comboplate, propette.

Materials: Lead(II) bromide, PbBr 2, naphthalene, C10H8, 0.1 mol dm-3

sodium

hydroxide, NaOH solution, 0.1 mol dm-3

glucose solution and 0.1 mol

dm-3

copper(II) sulphate, CuSO4 solution.

Procedure:

Caution: Carry out Part I of the experiment in the fume chamber.

I. Molten substances

Figure 6.1

1. Fill a microcrucible with solid lead(II) bromide until it is half full.

2. Set up the apparatus as shown in Figure 6.1.3. Using a microburner (refer to pg 11, Chap 1), heat the solid lead(II) bromide until

it has melted completely.4. Connect the battery clip of the LED to the terminals of the 9V battery and pencil

leads.

5. Immerse both the pencil leads into the molten lead(II) bromide.6. Record your observations in your notebook.

7. Repeat steps 1 to 6, replacing the solid lead(II) bromide with naphthalene.



40

II. Aqueous solutions

Figure 6.2

1. Use the propette to add sodium hydroxide solution into well E1. Rinse the

propette with tap water to clean it.

2. Push the lid with the current indicator into well E6.3. Connect the battery clip of the current indicator into well E6.

4. Connect each of the crocodile clip to the carbon rod (pencil leads) as shown in

Figure 6.2.5. Insert the carbon rod connected to the long black wire into solution in well E1.

Insert the carbon rod connected to the long end of the red wire into the same

solution in well E1. Make sure that the carbon rods do not touch in the solution.

6. Observe what happens to the red light emitting diode (LED) in the currentindicator. Wipe the carbon rods clean.

7. Repeat steps 1-6 using the copper(II) sulphate solution and glucose solution. Use

wells E2, F1 and F2.

Data and Observation:

Substance LED glow Does reaction occur Electrolyte or non-

electrolyte

Molten lead (II)

bromide

Molten naphthalene

Sodium hydroxide

solution

Glucose solution

Copper(II) sulphate

solution



41

Conclusions:

Questions:

1. What substances conduct electricity?

2. What substances do not conduct electricity?

3. What type of substances are electrolytes?4. What type of substances are non-electrolytes?

References:




42


B. Electrolysis of Molten compounds

Objective: To investigate the electrolysis of molten lead(II) bromide, PbBr2.

Apparatus: 9V battery, pencil leads, current indicator (LED) with wire connection,

microcrucible, microburner, microtripod stand and small wire gauze.

Materials: Lead(II) bromide, PbBr 2.

Procedure:

Figure 6.3

1. Fill a microcrucible with lead(II) bromide until it is half full.2. Place the microcrucible on the wire gauze.


4. Using the microburner (refer to pg 11, Chap 1), heat the solid lead(II) bromide

until it melts.5. Connect the battery clip of the current indicator to the terminals of the 9 V

battery.

6. Connect each of the crocodile clip to the pencil leads as shown in Figure 6.3.7. Immerse both of the pencil leads into the molten lead(II) bromide.

8. Observe what happens at the anode. Record all your observations in your

notebook.9. After 4 minutes, remove the crocodile clips from the pencil leads.

10. Carefully pour out the molten lead(II) bromide into a small beaker to observe

what is formed at the cathode.11. Record your observations in your notebook.



43


Electrode Observation Inference

Anode

Cathode

Conclusions:

Questions:

1. Name the ions that move to the cathode and the anode during electrolysis.

2. Write half equations that represent the reactions that occur at the

a) Anode b) Cathode

3. Write the overall equation that represents the electrolysis of lead(II) bromide,

PbBr 2.

References:





44


C. Investigating the electrolysis of aqueous solutions

Objective: To investigate the electrolysis of aqueous copper(II) sulphate, CuSO4

solution and sodium hydroxide, NaOH solution.

Apparatus: Comboplate, 9V battery, current indicator (LED) with wire connections, 2

straw electrodes, 1 straw electrode (with carbon electrode), 1 x carbonelectrode (pencil lead), sample vial, box of matches, thin stemmed propette.

Materials: 1.0 mol dm-3

sodium hydroxide, NaOH and 1.0 mol dm-3

copper(II) sulphate,CuSO4 solution.

Figure 6.4

Procedure:

I. Electrolysis of sodium hydroxide solution

1. Push the current indicator into well E6 of the comboplate.2. Mark each of the drinking straw electrodes using a permanent marker pen. Let

one of the electrodes be called electrode 1 and the other electrode 2.

3. Fill half of the sample vial with 1.0 mol dm-3

sodium hydroxide solution. Placethe vial into well E5 next to the current indicator in well E6.

4. Hold electrode 1 with the open end upwards and fill the electrode completely with

1.0 mol dm-3

sodium hydroxide solution from the propette.



45

5. Quickly turn electrode 1 the other way up and place it into the solution in the

small sample vial. Repeat this procedure for electrode 2. Return any remainingsolution in the propette to the small sample vial. Use tap water to thoroughly rinse

your fingers free of the sodium hydroxide solution.

6. Connect the end of the black wire from the current indicator to the negative (-)

terminal of the battery. Connect the end of the short black wire to electrode 1.7. Connect the end of the red wire to the positive terminal (+) of the battery. Connect

the other end of the red wire to electrode 2.

8. Let the substance produced in electrode 1 be called substance A. Let the substance produced in electrode 2 be called substance B.

9. Record any observation at the anode, cathode and in the electrolytes.

10. Test the gas gathered at the cathode by using a lighted splinter.11. Test the gas gathered at the anode by using a glowing splinter.

12. Record all the results.

II. Electrolysis of copper(II) sulphate solution

1. Push the current indicator into well E6 of the comboplate.

2. Fill half of the sample vial with 1.0 mol dm-3

copper(II) sulphate solution. Placethe vial into well E5 next to the current indicator in well E6.

3. Hold the straw electrode (with carbon electrode) with the open end upwards and

fill the electrode completely with 1.0 mol dm-3

copper(II) sulphate solution fromthe propette.

4. Quickly turn the electrode the other way up and place it into the solution in the

small sample vial. Return any remaining solution in the propette to the smallsample vial. Use tap water to thoroughly rinse your finger free of the copper(II)

sulphate solution.5. Place the carbon electrode (pencil lead) into the solution in the sample vial.

6. Connect the end black wire from the current indicator to the negative (-) terminal

of the battery. Connect the end of the short black wire to the carbon electrode.7. Connect the end of the red wire to the positive terminal (+) of the battery. Connect

the other end of the red wire to straw electrode.

8. Record any observation at the anode, cathode and in the electrolytes.

9. Light the match. Carefully remove straw electrode from the solution, sealing theopen end with your finger when it is out of the solution. Bring the electrode very

close to the glowing splinter.


Electrolyte Observations

Cathode Anode Change in solution

Sodium hydroxide

Copper(II)

sulphate



46

Conclusions:

Questions:

1. For the electrolysis of copper(II) sulphate solution,

a) Identify the cations and anions.

b) What are the ions that move to the anode and to the cathode?c) Which ions have been discharged at the anode and at the cathode?

d) Write half equations representing the reactions that occur at the anode and

the cathode.2. Draw a diagram which shows what happens during the electrolysis of dilute

sulphuric acid, H2SO4. The diagram should show:

a) The ions present in dilute sulphuric acid, H2SO4. b) The movement of ions to the anode and the cathode.

c) The discharge of ions at the anode and the cathode and their respective half

equations.

References:






47


D. Purification of copper

Objective: To investigate the purification of copper

Apparatus: 9V heavy duty battery, comboplate, current indicator (LED) with wire

connections, sample vial and thin stemmed propette.


copper(II) sulphate, CuSO4 solution, impure copper plate, pure

copper plate.

Figure 6.5

Procedure:

1. Push the current indicator into well E6 of the comboplate.2. Remove the lid from the small sample vial and fill half of the vial with 1.0 mol

dm-3

copper(II) sulphate solution. Place the vial into well E5 next to the current

indicator in well E6.3. The apparatus as shown in the figure 6.5 is set up using the impure copper plate as

the anode and the pure copper plate as the cathode.

4. Allow the electric current to pass through the electrolyte for 5 – 10 minutes.5. Record any changes at the anode and the cathode.

6. Repeat steps 1 to 5 using impure copper as the cathode and pure copper as the

anode.



48


Electrode

Observation

Anode Cathode Anode Cathode

Impure copper Pure copper

Pure copper Impure copper

Conclusions:

References:





49


E. Electroplating an object with copper

Objective: To investigate the electroplating of an object with copper

Apparatus: 9V heavy duty battery, comboplate, current indicator (LED) with wire

connections, sample vial and thin stemmed propette.


copper(II) sulphate solution, copper electrode/plate, iron nail,

sandpaper.

Figure 6.6

Procedure:

1. Clean a piece of iron nail with sand paper. Wash the iron nail with detergent andrinse thoroughly with water.

2. Push the current indicator into well E6 of the comboplate.

3. Remove the lid from a small sample vial and fill half of the vial with 1.0 mol dm-3

copper(II) sulphate solution. Place the vial into well E5 next to the current

indicator in well E6.

4. Set up the apparatus using the iron nail as the cathode and a copper electrode as

the anode as shown in figure 6.6.5. Switch the current off after 2 – 3 minutes.

6. Remove the iron nail from the electrolyte and dry it. Record the change to the iron

nail.7. Repeat steps 1 – 6 by using copper as the cathode and iron nail as the anode.



50


ElectrodeSet

Anode Cathode

Observation

I Copper Iron nail

II Iron nail Copper

Conclusions:

Questions:

1. What three conditions are necessary to electroplate an iron spoon with copper?

2. A good electroplating process is one that results in an even thin layer of coating.

Suggest 2 ways on how this can be achieved.

References:




51


F. Production of electricity from chemical reactions in a simple voltaic

cell

Objective: To show the production of electricity from chemical reactions in a simplevoltaic cell

Apparatus: 1 x Comboplate, 1 x thin stemmed propette, wire connections, 1 x voltmeter,1 x sample vial.


Sodium chloride, NaCl solution, copper plate and magnesiumribbon.

Figure 6.7

Procedure:

1. Clean a piece of magnesium ribbon and a copper plate with sandpaper.2. Fill half of the small sample vial with 1.0 mol dm

-3sodium chloride solution.

Place the vial into well E6.

3. Immerse the magnesium ribbon and copper plate in the sodium chloride solution

and connect both metals to the voltmeter/multimeter by using the wireconnections.

4. Record the reading of the voltmeter and any changes at the electrodes.

5. Repeat steps 1 to 4 using the copper plate instead of magnesium ribbon.



52


Type of metal Voltmeter reading (V) Observation

Magnesium/copper

(Mg/Cu)

Copper/copper (Cu/Cu)

Conclusions:

Questions:

1. Explain how electricity is produced in a simple voltaic cell. Give the half

equations for the reactions that take place.2. Predict what will happen if sodium chloride, NaCl solution is replaced by

potassium sulphate, K 2SO4 solution. Give your reasons.

References:





53


G. Production of electricity from chemical reactions in a Daniel cell

Objective: To show the production of electricity from chemical reactions in a Daniel

cell

Apparatus: 1 x comboplate, 2 x thin stemmed propette, 2 wire connections, 1 x

multimeter/voltmeter, filter paper, scissors.


copper(II) nitrate, Co(NO3)2 solution, 1.0 mol dm-3

zinc nitrate

Zn(NO3)2 solution, copper strip, zinc foil, potassium nitrate, KNO3, saturatedsolution.

Figure 6.8

Procedure:

1. Using the E row of the comboplate, fill half of E1 and E2 with copper(II) nitrate

and zinc nitrate solution respectively.

2. Make a salt bridge from the filter paper. Cut the paper into a shape given below sothat it will form a continuous bridge between 2 wells.



54

3. To make the salt bridge complete, place the cut out filter paper into a beaker

containing a saturated solution of potassium nitrate. Remove the salt bridge and place it into wells E1 and E2.

4. Clean up the copper plate and zinc foil with sand paper.

5. Immerse the copper plate in the copper(II) nitrate solution and zinc foil in the zinc

nitrate solution. Connect both metals to the voltmeter/multimeter using the wireconnections.

6. Observe what happens to the voltmeter, zinc foil, copper plate and copper(II)

nitrate solution.


Type of metal Observation

Zinc

Copper

Copper(II) sulphatesolution

Voltmeter

Conclusions:

References:


2. Tan, Y.T., Loh, W.L. & Tan, O.T. (2007). Success Chemistry SPM, Integrated

Curriculum for Secondary School, Oxford Fajar Sdn. Bhd: Shah Alam.

3. Microscale 30 Voltaic cells. http://dwb.unl.edu/Chemistry/MicroScale/MScale20.html

http://dwb.unl.edu/Chemistry/MicroScale/MScale20.html

http://dwb.unl.edu/Chemistry/MicroScale/MScale20.html



55


H. Constructing the electrochemical series using the principle of displacement of

metals

Objective: To construct the electrochemical series using the principle of displacement of metals

Apparatus: Comboplate, thin stemmed propette


copper(II) nitrate, Cu(NO3)2 solution, 1.0 mol dm-3

lead(II)

nitrate, Pb(NO3)2 solution, 1.0 mol dm-3

zinc nitrate, Zn (NO3)2 solution, 1.0mol dm

-3magnesium nitrate, Mg(NO3)2 solution, copper strip, lead strip, zinc

strip, magnesium ribbon and sand paper.

Figure 6.9

Procedure:

1. Fill half of F1, F2, F3 and F4 wells in the comboplate with copper(II) nitrate

solution.2. Clean a piece of copper strip, lead strip, zinc strip and magnesium ribbon

respectively with sand paper and drop into each of the wells.

3. Allow the reaction to proceed for five minutes.4. Observe any changes in the colour of the solution and whether any metals are

deposited.

5. Repeat step 1 to 4 by using lead(II) nitrate solution, zinc nitrate solution andmagnesium nitrate solution respectively to replace copper(II) nitrate solution.

6. Record the results of the experiment in a table below.



56


Solution

Metals

Copper(II) nitrate Lead(II) nitrate Zinc nitrate Magnesium

nitrate

Copper

Lead

Zinc

Magnesium

Conclusions:

Questions:

1. Why is magnesium not displaced by any other metals in this experiment?

2. Write the equations to show all displacement reactions involving zinc.

References:



2. Eng, N.H., Lim, E.W. & Lim, Y.C (2006).Focus excel chemistry form 4. Penerbitan

Pelangi Sdn. Bhd: Bangi.



57

Chapter 7: Acids and Bases

A. Investigating the role of water in showing the properties of acids

Objective: To investigate the role of water in showing the properties of acids

Apparatus: Comboplate, thin stemmed propettes, microspatula

Materials: Glacial ethanoic acid, CH3COOH, ethanol, C2H5OH, blue litmus paper, water.

1 2 3 4 5 6

F

E

D

C

Figure 7.1

Procedure:

1. Place a piece of dry blue litmus paper in well F1 of the comboplate.

2. Use the propette to draw up some dry glacial ethanoic acid.

3. Place a few drops of the glacial ethanoic acid onto the blue litmus paper.4. Observe the effect of the glacial ethanoic acid on the litmus paper. Record your

observations in the table.

5. Repeat steps 1 to 4 using ethanoic acid in water and ethanoic acid in ethanol toreplace glacial ethanoic acid in the wells F2 and F3.

6. Tabulate the observations in the table.

Blue litmus paper+

ethanoic

acid

Blue litmus paper+

ethanoic

acid+water

Blue litmus paper+

ethanoic

acid+

ethanol



58


Type of acid Observation

Glacial ethanoic acid, CH3COOH

Ethanoic acid, CH3COOH in water

Ethanoic acid, CH3COOH in ethanol

Conclusions:

Questions:

1. What is the ion responsible for changing the colour of blue litmus paper? How is

it produced?2. Why does glacial ethanoic acid, CH3COOH not show acidic properties?

3. When ethanoic acid, CH3COOH is dissolved in propanone, CH3COCH3, it does

not change the colour of blue litmus paper. Why?

4. When ethanoic acid is dissolved in water, it turns the litmus paper red. Why?

References:





59

Chapter 7: Acid and Bases

B. Studying the chemical properties of acids

Objective: To study the chemical properties of acids

Apparatus: 10 cm3

beaker, microspatula, filter funnel, retort stand and clamp, micro

burner, 25 cm3

conical flask, test tube, filter paper, wire gauze,

microtripod stand, microcrucible, 10 cm3

measuring cylinder.

Materials: Copper(II) oxide, CuO powder, zinc powder, 1 mol dm-3

sulphuric acid, 2

mol dm-3

nitric acid, HNO3, 2 mol dm-3

hydrochloric acid, HCl, calciumcarbonate, CaCO3, lime water, wooden splinter and filter paper.

I. Reactions of acids with bases

Figure 7.2



60

Procedure:

1. Pour about 5 cm3

of 1 mol dm-3

sulphuric acid, into a 10 cm3

beaker. Warm the

acid with a microburner (refer to pg 11, Chap 1).

2. Use a microspatula to add copper(II) oxide powder bit by bit into the acid. Stir the

mixture well.3. Continue adding copper(II) oxide until some of it no longer dissolves.

4. Remove the unreacted copper(II) oxide by filtration.

5. Pour the filtrate into a microcrucible. Gently heat the salt solution to produce asaturated solution.

6. Cool the saturated solution until crystals are formed.

7. Filter out the copper(II) sulphate crystals. Examine the crystals and record your observations in your notebook.


Test on acid Observation Inference

Heating with

copper(II) oxide

Questions:

1. How do you know that an acid-base reaction has occurred?2. How is the product of the reaction obtained?

3. What are the products of the reaction? Write an equation for the reaction.

4. Complete the following,

Acid + Base→ ___________ + ___________



61

II. Reactions of acids with metals

Figure 7.3

Procedure:

1. Pour 5 cm3

of 2 mol dm-3

hydrochloric acid into a 10 cm3 beaker. Warm the acid

with a microburner.2. Use a microspatula to add zinc powder bit by bit into the acid. Stir the mixture

well.

3. Test the gas produced by using a lighted splinter.4. Continue adding zinc powder until some of it no longer dissolves.

5. Remove the unreacted zinc powder by filtration.

6. Pour the filtrate into a microcrucible. Gently heat the salt solution to produce asaturated solution.

7. Cool the saturated solution until crystals are formed.8. Filter out the zinc sulphate crystals. Examine the crystals and record your

observations in your notebook.



Test with zinc powder



63



Test with calcium

carbonate

Questions:

1. Write an equation for the reaction between nitric acid and calcium carbonate.

What are the products formed?2. Complete the following.

Acid + Carbonate→ __________ + ___________ + ___________

Conclusions:

References:





64


C. Studying the chemical properties of bases

Objective: To study the chemical properties of bases

Apparatus: Comboplate, 10 cm3

beaker, microspatula, filter funnel, microburner, 25

cm3

conical flask, test tube, filter paper, wire gauze, microtripod stand,

microcrucible, 10 cm3

measuring cylinder.

Material: 1 mol dm-3

sodium hydroxide, NaOH solution, benzoic acid powder,

ammonium chloride, NH4Cl powder, iron(II) sulphate, FeSO4 solution,litmus paper.

I. Reactions of bases with acids

Figure 7.5

Procedure:

1. Pour about 5 cm3

of 1 mol dm-3

sodium hydroxide solution into a 10 cm3

beaker.

2. Use a microspatula to add benzoic acid powder bit by bit into the acid. Stir the mixture

well.



65

3. Continue adding benzoic acid until some of it no longer dissolves.

4. Remove the unreacted benzoic acid by filtration.5. Pour the filtrate into a microcrucible. Gently heat the salt solution with a microburner

(refer to pg 11, Chap 1) to produce a saturated solution.


7. Filter out the sodium benzoate crystals. Examine the crystals and record your observations in your notebook.

II. Reactions of bases with ammonium salts

Figure 7.6

Procedure:

1. Fill one third of well F1 of the comboplate with sodium hydroxide solution.2. Add a microspatula of ammonium chloride powder in the well.

3. Test the gas formed using moist red litmus paper.

4. Observe what happen to the litmus paper.

III. Reactions of bases with metal ions

Procedure:

1. Add 10 drops of iron(II) sulphate solution into the well F2 of the comboplate.

2. Add 1 drop of sodium hydroxide solution into the well. Observe what happen.


Test on sodium

hydroxide

Observation Inference

With benzoic acid

powder added



66

Heating withammonium chloride

powder

With iron(II) sulphate

solution

Conclusions:

References:




67


D. Measuring the pH of solutions used in daily life

Objective: To measure the pH of solutions used in daily life

Aparatus: Comboplate, thin stemmed propettes, microspatula.

Materials: Vinegar, lemon juice, soap solution, distilled water, carbonated drink, tapwater, rainwater, dilute hydrochloric acid, HCl and dilute sodium hydroxide,

NaOH solution, universal indicator solution

1 2 3 4 5 6 7 8 9

A

B

C

D

E

Figure 7.7

Procedure:

1. Add 10 drops of vinegar to well A1.

2. Add 10 drops of lemon juice to well A2.3. Add 10 drops of soap solution to well A3.

4. Add 10 drops of distilled water to well A4.5. Add 10 drops of carbonated drink to well A5.

6. Add 10 drops of tap water to well A6.

7. Add 10 drops of rainwater to well A7.8. Add 10 drops of dilute hydrochloric acid to well A8.

9. Add 10 drops of dilute sodium hydroxide to well A9.

Vinegar Lemon

juice Soap

solution

Distill-

ed

water

Carbona

-ted

drink

Tap

water

Rain

water

Dilute

HCl

Dilute

NaOH



68

10. Add 1 drop of universal indicator solution into each of the wells, A1 to A9.

11. Stir the solution in each well with a clean plastic microspatula.12. Observe the pH of all the solutions and record your observations in the table.


Well Number Colour of solution Proposed pH

A1 (Vinegar)A2 (Lemon juice)

A3 (Soap solution)

A4 (Distilled water)A5 (Carbonated drink)

A6 (Tap water)

A7 (Rain water)

A8 (HCl)

A9 (NaOH)

Conclusions:

References:







69


E. Determining the end point of the titration between hydrochloric acid, HCl and

sodium hydroxide, NaOH solution using an acid-base indicator.

Objective: To determine the end point of the titration between hydrochloric acid,HCl and sodium hydroxide, NaOH solution using an acid-base indicator

Apparatus: 1 x comboplate, 1 x microstand, 2 x microburette, 1 x syringe, 1 xmicrospatula, 1 x silicone tube, propettes and white paper.


hydrochloric acid, HCl, 0.1 mol dm-3

sodium hydroxide, NaOH, phenolphthalein solution.

Figure 7.8



70

Procedure:

1. Assemble the microburette as shown. Push the plastic microstand into well D2 of the

comboplate. Orient the pairs of arms on the central stem of the microstand so that one

arm of each pair is directly above well F1. Clip the assembled microburette into each

arm of the microstand above well F1.2. Put the comboplate on a piece of white paper.

3. Rinse the 2 cm3

microburette with the sodium hydroxide solution in the following

way:(i) Set up the microburette as in Figure 7.8 by attaching the plastic

syringe to the top of the 2 cm3

microburette using silicone tubing.

Place the plastic tip at the other end of the microburette.(ii) Rinse the microburette with sodium hydroxide. Use the syringe to fill

up the microburette through the plastic tip. Repeat this rinsing process

twice.

4. Fill the rinsed microburette with exactly 1.00 cm

3

of the sodium hydroxide solution.Dispense all this solution into well F1 of the comboplate. Repeat this step twice,

dispensing the 1.00 cm3

aliquots of sodium hydroxide into wells, F2 and F3.

5. Empty the microburette, rinse it with water.

6. Rinse the microburette at least three times with the hydrochloric acid, HCl.

7. Fill the microburette with the HCl to the 0.00 cm3

level (or there about). Read thelevel of the meniscus and record this as the initial volume of HCl (titration 1).

8. Use the thin stemmed propette to add one drop of phenolphthalein solution to the

NaOH in the well F1.

9. Position the microburette above the comboplate so that the tip of the microburette is

above well F1.

Note: Do not place the microburette too close to well F1 as the plastic

microspatula may knock against it during stirring of the solution in the well. Thismay cause drops of the solution to splash out of the well.

10. Push down gently on the syringe plunger and add one drop of HCl into well F1. Stir the solution in well F1 with plastic microspatula. Be careful not to spill any solution

out of the well. Leave the microspatula in the well during the titration.

11. Continue to add HCl from the microburette one drop at a time until the indicator

changes colour from pink to colourless. Stir the solution in well F1 after each drop is

added.

12. Observe the volume of HCl in the microburette and record this as the final volume.

Calculate the volume of HCl dispensed.



71

13. Refill the microburette with the HCl and record the initial volume (Titration 2).

14. Add one drop of phenolphthalein indicator to the NaOH in well F2. Position the

microburette above well F2 by moving the plastic microstand to another small well in

the D row of the comboplate.

15. Now, that you know the approximate volume of the HCl required to titrate the NaOH,

you can add the HCl a little more quickly than before until about 0.04 cm3

before theexpected end point. Stir thoroughly.

16. Add the HCl slowly, one drop at a time with stirring, until the indicator changes from pink to colourless. Record the final volume (Titration 3).

17. Repeat the titration in well F3.

Note: Reject any results where the end point has been overshot.


Titration No. 1 2 3

Volume of HCl/ cm3

Final burette reading (cm3)

Initial burette reading (cm3)

Volume of hydrochloric acid,HCl needed (cm

3)

Average volume of HCl used:

Conclusions:



72

Questions:

1. a) What is the average volume of HCl needed to neutralize 25.0 cm3

of NaOH?

b) Write the equation for the neutralization reaction.

2. a) How is the end point of the titration determined? b) How else could you determine the end point?

3. Explain the following:

a) A clean burette has to be rinsed with a little acid before filling it up. b) There must be no air bubbles in the tip of the burette.

c) Burette readings must be taken at eye level.

d) There is no need to rinse the conical flask with NaOH.

References:



2. Bell, B., Akoobhai, B. & Bradley, J. (2005). RADMASTE microtitration experiments.

Manual for secondary school learners. The UNESCO – Associated Centre for

Microscience Experiments.



73

Chapter 8: Salts

A. Solubility of nitrate, sulphate, carbonate and chloride salts.

Objective: To study the solubility of nitrate, sulphate, carbonate and chloride salts.

Apparatus: Comboplate, syringe, microspatula.

Materials: Lead(II) nitrate, Pb(NO3)2, copper(II) nitrate, Cu(NO3)2, magnesiumnitrate, Mg(NO3)2, zinc nitrate, Zn(NO3)2, calcium nitrate, Ca(NO3)2,

copper(II) sulphate, CuSO4, zinc sulphate, ZnSO4, barium sulphate,

BaSO4, magnesium sulphate, MgSO4, lead(II) sulphate, PbSO4, calciumsulphate, CaSO4,copper(II) carbonate, CuCO3, zinc carbonate, ZnCO3,

potassium carbonate, K 2CO3, sodium carbonate, Na2CO3, ammonium

carbonate, magnesium carbonate, MgCO3, copper(II) chloride, CuCl2, zincchloride, ZnCl2 and mercury chloride, HgCl2, magnesium chloride, MgCl2

lead(II) chloride, PbCl2 and silver chloride, AgCl.

Procedure:

Figure 8.1

1. Use a spooned end of a plastic microspatula to place 2 leveled spatulas of lead(II)

nitrate powder into well F1 of the comboplate.

2. Use a syringe to add 1 cm3

of distilled water to the well F1. Stir the mixture andnote the solubility of the salt.

3. Repeat steps 1 and 2 using copper(II) nitrate, magnesium nitrate, zinc

nitrate, calcium nitrate, copper(II) sulphate, zinc sulphate, barium sulphate,magnesium sulphate, lead(II) sulphate, calcium sulphate, copper(II) carbonate,

zinc carbonate, potassium carbonate, sodium carbonate, ammonium carbonate,

magnesium carbonate, copper(II) chloride, zinc chloride, mercury chloride,magnesium chloride, lead(II) chloride and silver chloride.



74


Type of salt Salt Solubility

Nitrate

Lead(II) nitrate

Copper(II) nitrate

Magnesium nitrateZinc nitrate

Calcium nitrate

Copper(II) sulphateZinc sulphate

Magnesium sulphateSulphate

Barium sulphate

Lead(II) sulphate

Calcium sulphate

Copper(II)chloride

Zinc chloride

Magnesium chlorideChlorideMercury chlorideLead(II) chloride

Silver chloride

Potassium carbonateSodium carbonate

Ammonium carbonateCarbonate

Copper(II) carbonate

Zinc carbonate

Magnesium carbonate

Conclusions:

References:





75

Chapter 8: Salts

B. Preparation of soluble salts by mixing acids with bases

Objective: To prepare soluble salts by mixing acids with bases

Apparatus: Comboplate, microstand, micro crossarms, microburette, pipette tip,

silicone tube, syringe, microspatula, propette, conical flask 10 ml,

microcrucible, microburner, microtripod stand, wire gauze.


hydrochloric acid, HCl, 2 mol dm-3

potassium hydroxide,

KOH, phenolphthalein.

Procedure:

I. To determine the volume of acid for neutralization

Figure 8.2



76

1. Use the microburette to transfer 2.0 cm3

of potassium hydroxide solution to a

conical flask. Use the propette to add one or two drops of phenolphthalein.2. Push the plastic microstand into well D1 of the comboplate. Orient the pairs of

arms on the central stem of the microstand so that one arm of each pair is directly

above the conical flask.

3. Fill the burette with hydrochloric acid, HCl and record the initial burette reading.4. Titrate carefully by slowly adding the acid into the conical flask and shake well.

5. Continue adding the acid until the indicator just turns from pink to colorless.

Record the final burette reading.6. Determine the volume of acid used to neutralize 2.0 cm

3of the base. (Let the

volume be V cm3).

II. Preparation of the salt

Figure 8.3

1. Use a microburette to transfer 2.0 cm3

of the same potassium hydroxide solution

into a 10 cm3

conical flask. Do not add any indicator.2. From the microburette, add exactly V cm

3of hydrochloric acid to the base and

shake well.

3. Pour the contents of the conical flask into a microcrucible.4. Gently heat the solution to evaporate most of the water to produce a saturated

solution with a microburner.

5. Cool the hot saturated salt solution for crystallization to occur.

6. Filter to obtain the potassium chloride crystals.

III. Recrystallisation of the salt.

1. Place the potassium chloride crystals in a 10 cm3

beaker.

2. Add just enough distilled water to cover the crystals. Gently heat the solution and

stir with a microspatula.3. Filter to remove impurities and pour the filtrate into a microcrucible.



78

Chapter 8: Salts

C. Preparation of soluble salts by mixing an acid with an insoluble metal oxide

Objective: To prepare soluble salts by mixing an acid with an insoluble metal oxide

Apparatus: 10 cm3

beaker, microspatula, filter funnel, microburner, 25 cm3

conical

flask, filter paper, wire gauze, microtripod stand, microcrucible, 10 cm3

measuring cylinder.


sulphuric acid, H2SO4 and copper(II) oxide, CuO powder.

Procedure:

Figure 8.4

1. Pour 5 cm3 of 2 mol dm-3 sulphuric acid into a 10 cm3 beaker. Warm the acid witha microburner (refer to pg 11, Chap 1).

2. Use a microspatula to add copper(II) oxide powder bit by bit into the acid. Stir the

mixture well.3. Continue adding copper(II) oxide until some of it no longer dissolves.

4. Remove the unreacted copper(II) oxide by filtration.

5. Pour the filtrate into a microcrucible. Gently heat the salt solution to produce a

saturated solution.



79


7. Filter out the copper(II) sulphate crystals.8. Carry out a crystallization to obtain pure copper(II) sulphate crystals.

9. Study the physical properties of the crystal and record your observation in your

notebook.


Conclusions:

Questions:

1. Give the equation for the reaction between HNO3 and copper(II) oxide.

2. Name another salt that can be prepared from the reaction between an acid and aninsoluble metal oxide.

References:





80

Chapter 8: Salts

D. Preparation of insoluble salts by carrying out a precipitation reaction

Objective: To prepare insoluble salts by carrying out a precipitation reaction

Apparatus: 10 cm3

beaker, microspatula, 25 cm3

conical flasks, filter funnel, filter

paper and syringe.


lead(II) nitrate, Pb(NO3)2, potassium iodide, KI, potassium

chromate(IV), K 2Cr 2O7, sodium sulphate, Na2SO4, and barium chloride,

BaCl2 solution.

Procedure:

I. Preparation of lead(II) iodide

Figure 8.5

1. Add about 0.5 cm3

of 0.5 mol dm-3

lead(II) nitrate solution and 0.5 cm3of

0.5 mol dm-3

potassium iodide solution in a 10 cm3

beaker.

2. Stir the mixture thoroughly with a microspatula. A yellow precipitate forms

immediately.

3. Filter the mixture to obtain the yellow lead(II) iodide as the residue.4. Rinse the residue with distilled water to remove any traces of other ions in it.

5. Dry the yellow residue by pressing it between two pieces of filter paper.

II. Preparation of lead(II) chromate(VI)


of 0.5 mol dm-3

lead(II) nitrate solution and 0.5 cm3

of 0.5 mol

dm-3

potassium chromate(VI) solution in a 10 cm3

beaker.

2. Stir the mixture thoroughly with a microspatula. A yellow precipitate forms

immediately.



81

3. Filter the mixture to obtain the yellow lead(II) chromate(VI) as the residue.

4. Rinse the residue with distilled water and dry it between two pieces of filter paper.

III. Preparation of barium sulphate


of 0.5 mol dm-3

barium chloride solution and 0.5 cm3

of 0.5

mol dm-3

sodium sulphate solution in a 10 cm3

beaker.2. Stir the mixture thoroughly with a microspatula. A white precipitate forms

immediately.

3. Filter the mixture to obtain the white barium sulphate as the residue.4. Rinse the residue with distilled water and dry it between two pieces of filter

paper.


Conclusions:

Questions:

1. Give the equations for the preparation of the three salts.

2. Can this kind of reaction be used prepare NH4Cl? Give reasons for your answer.

3. PbCrO4 cannot be purified by recrystallisation. Why?

References:





82

Chapter 8: Salts

E. Constructing the ionic equation for the formation of lead(II) chromate(VI)

Objective: To construct the ionic equation for the formation of lead(II)

chromate(VI).

Apparatus: Comboplate, Durham tubes, prestick/plasticine, microburette, syringe and

ruler.


lead(II) nitrate, Pb(NO3)2 solution, 0.5 mol dm-3

potassium

chromate, K 2Cr 2O7 solution.

Procedure:

Figure 8.6

1. Label seven Durham tubes of the same size from 1 to 7 and place them in the

bigger wells of the comboplate.

2. Fill the syringe 0.5 mol dm-3

potassium chromate(VI) solution. Run in 0.5 cm3

of the potassium chromate(VI) solution into each of the seven Durham tubes.

3. Fill the microburette with 0.5 mol dm-3

lead(II) nitrate solution. Add 0.10, 0.20,0.30, 0.40, 0.50, 0.60 and 0.70 cm

3lead(II) nitrate to each of the seven Durham

tubes respectively.4. Shake each Durham tube well.

5. Place all the tubes in the smaller wells of the comboplate vertically using

prestick/plasticine.6. Leave it aside for about half an hour to allow the precipitate to settle.

7. Measure the height of the precipitate in each Durham tube.



83

8. Note the colour of the solution above the precipitate in each tube.

9. Record your readings and observations in your notebook as shown in Table below.

10. Plot a graph of precipitate height against volume of lead(II) nitrate solution.


Durham Tube 1 2 3 4 5 6 7

Volume of 0.5 mol dm-3

potassium chromate

(VI) solution (cm3)

0.5 0.5 0.5 0.5 0.5 0.5 0.5

Volume of 0.5 mol dm-3

lead(II) nitrate solution(cm

3)

0.1 0.2 0.3 0.4 0.5 0.6 0.7

Height of precipitate (cm)

Colour of solution above precipitate

Conclusions:

Questions:

1. Why must you have the volume of Pb(NO3)2 constant?2. Why are different volumes of potassium chromate(VI) added to each test tube?3. Why does the colour of the solution above the precipitate change?

4. How does the height of the precipitate formed change? Why?

References:




84

Chapter 8: Salts

F. Carrying out chemical tests to identify gases

Objective: To carry out chemical tests to identify gases.

Apparatus: Comboplate, silicone tube, lid 1, lid 2, syringe, microspatula, glass rod,

W-tube, microburner, combustion and fusion tube, toothpick, propette,

forceps.

Materials: Manganese dioxide, MnO2 powder, fresh hydrogen peroxide solution,

H2O2 (10%), 2 mol dm-3

sulphuric acid, H2SO4, zinc, Zn powder, calciumcarbonate, CaCO3 powder, dilute hydrochloric acid, HCl, lime water,

dilute sodium hydroxide, NaOH solution, ammonium chloride, NH4Cl

powder, household bleach solution, 2 mol dm-3

hydrochloric acid, HCl,sodium chloride, NaCl powder, concentrated sulphuric acid, H2SO4,

concentrated ammonia, NH3, dilute acidified potassium manganate(VII),KMnO4 solution, sodium sulphate, Na2SO4 powder, lead(II) nitrate,

Pb(NO3)2 powder.

Procedure:

I. Test for oxygen gas, O2

Figure 8.7

1. Use the spooned end of a plastic microspatula to place one leveled spatula of manganese dioxide powder into well F1 of the comboplate.

2. Seal the well securely with lid 1.



85

3. Attach a piece of silicone tubing to the tube connector on lid 1 so that it slants

away from the syringe inlet.4. Connect the free end of the silicone tube to the glass combustion tube as shown in

Figure 8.6.


of freshly prepared 10% hydrogen peroxide solution.

6. Fit the syringe into the syringe inlet on lid 1, but do not add the hydrogen peroxide to the well yet.

7. Light the microburner (refer to pg 11, Chap 1) and put it down away from the

comboplate.8. Take the toothpick and hold the narrow end of the splint in the flame of the

microburner until it begins to burn.

9. While the top 1 to 2 cm of the splint is burning, slowly add the hydrogen peroxideto the manganese dioxide in the well.

10. When the end of the splint is glowing red, put out the flame by either blowing

softly on the splint or shaking it gently.11. Hold the glowing portion of the splint just above the open end of the glass tube

and observe what happens.

II. Test for hydrogen gas, H2

Figure 8.8

1. Using the propette, add half of well F2 with 2 mol dm-3

hydrochloric acid.

2. Add 1-2 leveled spatulas (spooned end) of zinc powder in the well.

3. Light a match, hold it horizontally placing the flame at the mouth of the well and

observe what happens.



86

III. Test for carbon dioxide gas, CO2

Figure 8.9

1. Using the spooned end of the microspatula, place 2 leveled spatulas of calcium

carbonate powder into well F3.

2. Cover well F3 with lid 1.3. Using a clean propette, fill ¾ of the well F4 with the limewater. Cover well F4

with lid 2.

4. Join well F3 to well F4 by attaching the silicone tube to the tube connectors onlids of wells F3 and F4.


of dilute hydrochloric acid. Fit the syringe into lid 1

on well F3.

6. Add the acid dropwise to the calcium carbonate powder in well F3. Observe whathappens.

IV. Test for ammonia gas, NH3

Figure 8.10



87

1. Using the propette, add half of well F5 with dilute sodium hydroxide solution.2. Add 1 leveled spatula of ammonium chloride into the well and stir the mixture

with a microspatula.

3. Bring a piece of moist red litmus paper to the mouth of the well. Observe what

happens to the litmus paper.

V. Test for chlorine gas

Figure 8.11

1. Using the propette, add half of well F6 with household bleach.2. Cover well F6 with lid 1.


of 2 mol dm-3

hydrochloric acid. Fit the syringe into

lid 1 on well F6.4. Add the acid dropwise to the bleach in well F6.

5. Bring the moist blue litmus paper above the connector of lid 1 and observe what

happens.

VI. Test for hydrogen chloride gas, HCl

Figure 8.12



88

1. Place 1 leveled spatula of sodium chloride in well F1.

2. Using a propette, add 5-6 drops of concentrated sulphuric acid in well E1.3. Immerse the glass rod in the concentrated ammonia solution and bring it to the

mouth of well E1. Observe what happens.

VII. Test for sulphur dioxide gas, SO2

Figure 8.13

1. Using a propette, place a few drops of acidified potassium manganate(VII)solution in one angle of W-tube.

2. Use the spooned end of a microspatula to put sodium sulphate powder in another

angle.3. Add 2 drops of 2 mol dm

-3hydrochloric acid in sodium sulphate powder.

4. Use a microburner to heat the mixture and use moist blue litmus paper to test the

gas formed.

5. Observe what happens to the litmus paper and acidified potassium manganate(VII) solution.



89

VIII. Test for nitrogen dioxide gas, NO2.

Figure 8.14

1. Use the narrow end of microspatula to place the lead(II) nitrate powder in a clean

glass fusion tube.

2. Hold the fusion tube using the forceps.3. Heat the fusion tube with lead(II) nitrate slowly at first and then stronger. Test the

gases formed using moist blue litmus paper.4. Record the colour of the gas and any changes happen to the litmus paper.


Name of gasColour of

gasSmell of

gasEffect on damp

litmusConfirmatory test on gas

Oxygen gas,

O2

Hydrogengas, H2

Carbon

dioxide gas,

CO2

Ammoniagas, NH3

Chlorine gas,Cl2



91

Chapter 8: Salts

G. Studying the effect of heat on carbonate and nitrate salts

Objective: To study the effect of heat on carbonate and nitrate salts.

Apparatus: Comboplate, silicone tube, lid 2, glass fusion tube, propettes, crossarms

for the microstand, microspatula, microburner, prestik/plasticine, forceps,

splinter.

Materials: Copper(II) carbonate, CuCO3, zinc carbonate, ZnCO3, lead(II) carbonate,

PbCO3, sodium carbonate, Na2CO3, calcium carbonate, CaCO3, potassiumcarbonate, K 2CO3, magnesium carbonate, MgCO3, sodium nitrate, NaNO3,

calcium nitrate, Ca(NO3)2, zinc nitrate, Zn(NO3)2, iron(II) nitrate,

Fe(NO3)2, iron(III) nitrate, Fe(NO3)3, lead(II) nitrate, Pb(NO3)2, copper(II)nitrate, Cu(NO3)2 and potassium nitrate, KNO3.

Procedure:

I. Carbonate salts

Figure 8.15

1. Hold the fusion tube in a horizontal position. Use the narrow end of a plastic

microspatula to fill about ½ of the fusion tube with copper(II) carbonate powder.

2. Set up the apparatus as shown in Figure 8.13 (refer to pg 11, Chap 1 to set upmicroburner).

3. Heat the carbonate salt strongly.4. Observe any changes that occur to the lime water.

5. Observe the color of the residue when it is hot and when it is cold.

6. Repeat steps 1 to 5 using each of the carbonates listed in the following table toreplace the copper(II) carbonate.

7. Record all your observations in your notebook.



92


Color of residueCarbonate salt

Color of salt

before heating Hot ColdEffect on limewater

Copper(II)

carbonate, CuCO3 Zinc carbonate,

ZnCO3

Lead(II) carbonate,PbCO3

Sodium carbonate, Na2CO3

Calcium carbonate,

CaCO3

Potassium

carbonate, K 2CO3

Magnesiumcarbonate, MgCO3

Discussion:

1. What role does lime water play in this experiment?

2. Name the gas produced in this experiment.

3. a) What are the carbonates that can be decomposed by heat? b) Write an equation to represent the decomposition of each carbonate salt.

4. What are the carbonate salts that are not decomposed by heat?

5. What can you infer from the colour change(s) that occur during heating of the

carbonate salts?

II. Nitrate salts

Figure 8.16



93

1. Use the narrow end of a microspatula to place the sodium nitrate powder in a

clean glass fusion tube.2. Hold the fusion tube using a pair of forceps.

3. Heat the fusion tube slowly and then stronger. Test the gases formed with the

splinter and litmus paper.

4. Record the colour of the gas and any changes that happens to the solid in thefusion tube.

5. Leave the residue in the fusion tube to cool and record its colour.

6. Repeat steps 1 to 5 using each of the nitrate salts listed in the table to replacesodium nitrate.

7. Record all your observations in your notebook.


Colour of residue Nitrate salts

Colour of

salt before

heating

Hot Cold

Effect on

damp blue

litmus paper

Effect on glowing

wooden splinter

Sodium nitrate,

NaNO3

Calcium nitrate,

Ca(NO3)2

Magnesium

nitrate, Mg(NO3)2

Zinc nitrate,

Zn(NO3)2

Iron(II) nitrate,

Fe(NO3)2

Iron(III) nitrate,Fe(NO3)3

Lead(II) nitrate,

Pb(NO3)2

Copper(II) nitrate,

Cu(NO3)2

Potassium nitrate,

KNO3

Questions:

1. Do all nitrates salts decompose to produce the same salts? Justify your answer with your observations.

2. Write an equation for the decomposition of each nitrate salt.



94

Conclusions:

References:





3. Tan, Y.T., Loh, W.L. & Tan, O.T. (2007). Success chemistry SPM, Integrated Curriculum for Secondary School, Oxford Fajar Sdn. Bhd: Shah Alam



95

Chapter 8: Salts

H. Testing for the presence of anions in aqueous solutions

Objective: To test for the presence of anions in aqueous solutions

Apparatus: Comboplate, silicone tube, lid 1, lid 2, syringe, propette and microspatula.


sodium carbonate, Na2CO3 solution, 1 mol dm-3

sodiumchloride, NaCl, 1 mol dm

-3sodium sulphate, Na2SO4 solution, 1 mol dm

-3

sodium nitrate, NaNO3 solution, 1 mol dm-3

iron(II) sulphate, FeSO4

solution, 0.1 mol dm-3

silver nitrate, AgNO3 solution, 1 mol dm-3

bariumchloride, BaCl2, 1 mol dm

-3sulphuric acid, H2SO4, 2 mol dm

-3

hydrochloric acid, HCl, 2 mol dm-3

nitric acid, HNO3, red litmus paper,

concentrated sulphuric acid, H2SO4 and lime water.

Procedure:

I. Test for carbonate ion, CO32-

Figure 8.17

1. Using a propette, fill 1/3 of well F1 with sodium carbonate solution.

2. Cover well F1 with lid 1.

3. Using a clean propette, fill ¾ of well F2 with the lime water. Cover well F2 withlid 2.4. Join well F1 to well F2 by attaching the silicone tube to the tube connectors on

lids of well F1 and F2.


hydrochloric acid. Fit the syringe into lid 1 on wellF1.

6. Add the acid dropwise to the sodium carbonate solution in well F1. Observe what

happens to the lime water.



96

II. Test for chloride ion, Cl-

Figure 8.18

1. Using a propette, fill 1/3 of well F3 with the sodium chloride, NaCl solution.

2. Add 10 drops of nitric acid into the well F3.3. Add 10 drops of silver nitrate solution to the mixture in well F3.

4. Stir the mixture using the microspatula and observe what happens.

III. Test for sulphate ion, SO42-

Figure 8.19

1. Using a propette, fill 1/3 of the well F4 with the sodium sulphate solution.

2. Add 10 drops of hydrochloric acid into the well F4.

3. Add 10 drops of barium chloride solution to the mixture in well F4.

4. Stir the mixture using the microspatula and observe what happens.



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IV. Test for nitrate ion, NO3-

Figure 8.20

1. Using a propette, fill 1/3 of the well F5 with sodium nitrate solution.

2. Add 10 drops of sulphuric acid into the well F5.

3. Add 10 drops of iron(II) sulphate solution to the mixture. Stir the mixture using

microspatula to mix well.4. Carefully, add 10 drops of concentrated sulphuric acid down the slide of the well

F5. Do not stir the mixture. Observe what happens.


Test Observation Inference

Carbonate ion, CO3-2

Chloride ion, Cl-

Sulphate ion, SO42-

Nitrate ion, NO3-



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Conclusions:

Questions:

1. Give the ionic equation for the reaction between an acid and a carbonate ion.

2. a) What is the white precipitate formed in the test for Cl-?

b) Write the ionic equation.3. a) What is the white precipitate formed in the test for SO4

2-?

b) Write the ionic equation.

4. Why must the solutions be acidified first in the tests for Cl-, SO4

2-and NO3

-?

5. Set up a table showing the test and results for each anion.

References:


Chemistry practical book form 4,Abadi Ilmu Sdn. Bhd: Petaling Jaya.



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Chapter 9: Manufactured Substances in Industry

A. Preparation of ammonium sulphate fertilizer

Objective: To prepare ammonium sulphate, (NH4)2SO4 fertilizer

Apparatus: Comboplate, microstand, micro crossarms, microburette, pipette tip,

silicone tube, syringe, microspatula, propette, 10 cm3

conical flask,

microcrucible, microburner, microtripod stand, wire gauze, filter funnel,filter paper, 25 cm

3conical flask.


sulphuric acid, H2SO4 and 2.0 mol dm-3

ammonia, NH3 solution, phenolphthalein.

Procedure:

I. To determine the volume of acid for neutralization

Figure 9.1



100


of ammonia solution to a conical flask.

Use a propette to add one or two drops of phenolphthalein.2. Push the plastic microstand into well D1 of the comboplate. Orient the pairs of

arms on the central stem of the microstand so that one arm of each pair is directly

above the conical flask.

3. Fill a clean microburette with sulphuric acid and record the initial burette reading.4. Titrate carefully by slowly adding the acid into the conical flask and stirring well

with a microspatula.

5. Continue adding the acid until the indicator just turns from pink to colourless.Record the final burette reading.

6. Determine the volume of acid used to neutralize 2.0 cm3

of the base. (let the

volume be V cm3).

II. Preparation of the salt

Figure 9.2


of the same ammonia solution into a 10cm

3conical flask. Do not add any indicator.

2. From the burette, add exactly V cm3

of sulphuric acid to the ammonia solution

and stir well.3. Pour the contents of the conical flask into a microcrucible.

4. Gently heat the solution with a microburner to evaporate most of the water to produce a saturated solution.

5. Stop the heating and cool the hot saturated salt solution in order for crystallization

to occur.

6. Filter to obtain the ammonium sulphate crystals and dry it using 2 pieces of filter paper.



* If the salts have crystallized in the microcrucible, there is no need to filter thesolution. Just scoop out the crystals using a microspatula onto a piece of filter paper

and dry them.


Conclusions:

Questions:

1. Write a balanced equation for the reaction between NH3 and H2SO4.

2. Calculate the theoretical yield of ammonium sulphate crystals you can obtain based on your preparation.

3. The mass of ammonium sulphate, (NH4)2SO4 crystals obtained from your

experiment will be less than the theoretical value.

R f

Chapter 2 Experiment

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Transcript of Chapter 2 Experiment