GENERAL CHEMISTRY Laboratory Guide This module provides a laboratory guidelines, safety declaration form, Lab Report guidelines and Laboratory manual for subject of General Chemistry (CLD 10004). Mohd Zulkhairi Abdul Rahim

Laboratory Information

Before each lab session, you should prepare by reading the lab manual and the textbook required reading. We expect you to have a good understanding of the purpose, details of the

procedure, the use of all chemicals and any significant hazards, and the underlying science of the experiment when you come to lab.

TABLE OF CONTENTS

Page

TITLE PAGE

INTRODUCTION

LABORATORY SAFETY GUIDELINES

SAFETY DECLARATION FORM

CHEMISTRY LABORATORY REPORT QUIDELINES

EXPERIMENT

3

1 Calibration of Volumetric Glassware

3

2 Empirical Formulas

3

3 Standardization of Sodium Hydroxide Solutions

10

4 Acids, Bases, Buffers and The Determination of pH

24

5 Redox Reactions

29

6

Qualitative Analysis of Common Ions

REFERENCES

103

APPENDICES

113

INTRODUCTION

This manual provides laboratory guidelines, safety declaration form, Chemistry Lab

Report guidelines and Laboratory manual for subject of Chemistry (CLB 10203).

The primary purpose of this manual is to compile all necessary information regrading

laboratory component in one manual.

The manual contains four parts. Part 1 provides a description of the general requirements of a

thesis produced in UniKL MICET, which should be useful to the student. Part 2 containing

requirements for format and arrangement of research proposal which the student intends to

undertake in the completed thesis. Part 3 explains the different parts of the thesis manuscript

and how it is organized. Part 4 is on formatting of the thesis which the student will find necessary at the end of the thesis writing prior to submission.

Upon successful completion of this course, students will understand safety, transfer and

measurement of chemicals, using physical properties to identify compounds, chemical

reactions, paper chromatography, and pH. Students will gain experience in a variety of

laboratory techniques to safely conduct chemical experiments and procedures.

Students will be able to independently perform accurate quantitative measurements,

interpret experimental results, perform calculations on these results and draw a

reasonable, accurate conclusion.

Students will synthesize, isolate, purify and characterize a series of compounds using

modern methods. Students will demonstrate knowledge of proper use of modern

instrumental techniques. Students will be able to design an experimental procedure. Students will observe safe practices in the laboratory and will know how to respond in an

emergency.

Students will learn to gather hazardous materials information and will recognize and respond

properly to potential hazards of handling chemicals and chemical waste. There may be

shortcomings which we had overlooked but we pray that these should not hinder the process

of producing a quality thesis. We welcome all suggestions and criticism, which could be later,

included in future editions.

LABORATORY SAFETY GUIDELINES

General Guidelines

1. Conduct yourself in a responsible manner at all times in the laboratory.

2. Be familiar with your lab assignment before you come to the lab. Follow all written and verbal

instructions carefully. If you do not understand a direction or part of a procedure, ask the

instructor before proceeding.

3. No student may work in laboratory alone. The lab instructor or co-coordinator grant exceptions

on a case by case basis.

4. When first entering a laboratory, do not touch any equipment, chemicals or other materials in

the laboratory area until you are instructed to do so.

5. Do not eat, drink beverages or chew gum in the laboratory. Do not use laboratory glassware as

containers for food or beverages.

6. Smoking is not allowed in any indoor area.

7. No music allowed in the laboratory. Radio (including walkman) and other entertainment

devices are not permitted.

8. No cellular phone is allowed in this laboratory.

9. Perform only those experiments authorized by the instructor. Never do anything in the

laboratory that is not called for the laboratory procedures or by your instructor. Carefully

follow all instructions, both written and oral. Unauthorized experiments are prohibited.

10. Observe good housekeeping practices. Work areas should be kept clean and tidy at all times.

11. Horseplay, practical jokes, and pranks are dangerous and prohibited.

12. Always work in a well-ventilated area.

13. Bring only your laboratory instructions, worksheets and report to the work area. Other

materials (books, purses, backpacks, etc) should be stored in the cabinet.

14. Know the locations and operation procedures of all safety equipment including the first aid kit,

eyewash station, safety shower, spill kit and fire extinguisher.

15. Be alert and proceed with caution at all times in the laboratory. Notify the instructor

immediately of any unsafe condition you observe.

16. Label and equipment instructions must be read carefully before use. Set up and use the

prescribed apparatus as directed in the laboratory instructions provided by your instructor.

17. Experiments must be personally monitored at all times. You will be assigned a laboratory

station at which to work. Do not wander around the room, distract other students or interfere

with laboratory experiments or others.

18. Write your name and equipment use every time you come in to the laboratory in the log book.

19. Defeating safety devices or using equipment in a manner other than that which is intended will

be grounds for dismissal from the lab.

Clothing

1. Safety goggles and safety jacket must be worn whenever you work in lab.

2. Gloves should be worn whenever you use chemicals that cause skin irritations or need to

handle hot equipment.

3. Mask should be worn every time you prepare the chemicals.

4. Safety shoes and hard hat should be worn at all times while in the laboratory.

5. Contact lenses should not be worn in the laboratory unless you have permission from your

instructor.

6. Dress properly during a laboratory activity.

7. Long hair, dangling jewelry and loose or baggy clothing are a hazard in the laboratory. Long

hair must be tied back and dangling jewelry and loose or baggy clothing must be secured.

8. Sandal, open-toed shoes, high heels or shoes with holes in the sols will not be worn in the lab.

9. Short and skirts are not permitted.

10. Instructor and laboratory assistant have a right dismiss to you from the laboratory if they found

that you are not wearing proper safety clothing.

Handling Chemicals

1. Treat chemicals with respect and understand the chemicals you are using with Material Safety

Data Sheet (MSDS). The MSDS are available in the analytical room.

2. All chemicals in the laboratory are to be considered dangerous. Do not touch, taste or smell

any chemical unless specifically instructed to do so.

3. Check the label on chemical bottles before removing any of the contents. Take only much

chemical are you need. Smaller amounts often work better than larger amounts.

4. Label all containers and massing papers holding dry chemicals.

5. Never return unused chemicals to their original containers.

6. Never use mouth suction to fill a pipette. Use pipette bulb or pipette filler.

7. Acids must be handled with extreme care. Always add acids slowly to water, with slow stirring

and swirling, being careful of the heat produced, particularly with sulfuric acid.

8. Handle flammable hazardous liquid over a pan to contain spills. Never dispense flammable

liquids anywhere near a flame or source of heat.

9. Never take chemicals or other materials from the laboratory area.

10. Take good care when transferring acids and other chemicals from one part of the laboratory to

another. Hold them securely and in the method demonstrated by the instructor as you walk.

11. All wastes generated during the course of an experiment must be disposed of according to the

12. Never mix chemicals in sink drains.

13. Sinks are to be used only for water and those solutions designated by the instructor.

14. Solid chemicals, metals, matches, filter paper, and all other insoluble materials are to be

disposed of in the proper waste containers, not in the sink.

15. Checks the label of all waste containers twice before adding your chemicals waste to the

container.

16.

17. Keep hands away from your face, eyes, mouth and body while using chemicals. Wash your

hands with soap and water after performing all experiments.

Personal Hygiene

1. Wash hands before leaving the lab and before eating.

Gloves should be removed before leaving the lab, using telephones, or entering common areas.

Accidents and Injuries

1. Report any accidents (spill, breakage, etc) or injury (cut, burn, etc) to the instructor

immediately, no matter how trivial it may appear.

2. If you or your lab partners are hurt, immediately tell to the instructor.

3. If a chemical should splash in your eye(s), immediately flush with running water from the

eyewash station for at least 20 minutes. Notify the instructor immediately.

4. Spills should be cleaned up immediately.

Handling Glassware and Equipment

1. Inserting and removing glass tubing from rubber stopper can be dangerous. Always lubricate

glassware (tubing, thistle tubes, thermometer, etc) before attempting to insert it in a stopper.

Always protect your hands with tower or cotton gloves when inserting glass tubing into, or

removing it from a rubber stopper.

2. When removing an electrical plug from its socket, grasp the plug, not the electrical cord.

3. Hands must be completely dry before touching an electrical switch, plug or outlet.

4. Examine glassware before each use. Never use chipped or cracked glassware.

5. Never use dirty glassware.

6. Do not immerse hot glassware in cold water; it may shatter.

7. Report damaged electrical equipment immediately. Look for things such as frayed cords,

exposed wires and loose connections. Do not use damaged electrical equipment.

8. If you do not understand how to use a piece of equipment, ask the instructor for help.

9. Be careful when lifting heavy objects. Lift comfortably, avoid unnecessary bending, twisting,

reaching out, and excessive weights, lift gradually and keep in good physical shape.

10. Do not transfer a glassware form one laboratory to another without permission from instructor.

Heating Substances

1. Do not operate a hot plate by yourself. Take care that hair, clothing, and hands are a safe

distance from the hot plate at all times. Use of hot plate is only allowed in the presence of the

teacher.

2. Heated glassware remains very hot for a long time. They should be set aside in a designated

place to cool, and picked up with caution. Use tongs or heat protective gloves if necessary.

3. Never look into a container that is being heated.

4. Do not place hot apparatus directly on the laboratory desk. Always use an insulated

pad. Allow plenty of time for hot apparatus to cool before touching it.

5. If leaving a lab unattended, turn off all ignition sources and lock the doors.

Ended the Experiments

1. At the end of the laboratory sessions, you should;

Shut-off main gas outlet

Turn-off the water inlet

Desk top, floor area and sink are clean

All equipment is cool, clean and arranged

2. All equipment use should be flushed using deionized water.

SAFETY DECLARATION FORM

The Dean/Head of Campus

Universiti Kuala Lumpur

Malaysian Institute of Chemical and Bioengineering Technology

Lot 1988, Vendor City Industrial Area

Taboh Naning, 78000 Alor Gajah

Malacca

Dear Sir,

SAFETY DECLARATION

in UniKL MICET. I hereby agree to abide by all the rules and regulations stated in the safety

guidelines.

2. I hereby understood the contents and will disciplinary action will be taken against me, if I do

not abide by the stated rules.

3. I am fully responsible for all my actions during laboratory sessions.

Thank you.

Yours faithfully,

Name:

Matrix No:

Subject:

Date:

CHEMISTRY LAB REPORT FORMAT

You should type your lab report, but you may draw or write by hand any tables, diagrams, or

chemical equations as long as you do it neatly. Make sure that you check your document for

any spelling errors. Each lab report is worth 100 points.

You should also read the student handbook on the subject of plagiarism. Your data and

observations will be similar, but your interpretations should not be written identically. You

may not copy another student's lab report in part or in its entirety. If you are found guilty of

this infraction, you and the person from whom you copied will both lose points. In extreme

cases or repeated offenses, both students may receive a zero for the lab.

Title

Use a separate title page. Include the title of the experiment, YOUR NAME, and the date.

Also clearly indicate the name(s) of your lab partner(s).

Purpose

Write a few sentences describing what you are supposed to learn by doing the experiment. You

might write about learning the lab procedures themselves. Do not just copy word for word

from the lab handout.

Materials

List the chemicals and equipment needed to perform the experiment.

Procedure

Briefly list or summarize the procedure. Again, DO NOT COPY DIRECTLY from the lab

handout. Use your own words.

Data

Include any data, qualitative and quantitative, that you collect. This includes any observations.

You should include the proper units with any numbers, as well as use the proper number of

significant figures based upon the lab equipment used. Remember, read the last known place

and estimate one more digit. DO NOT place any calculations or data analysis in this section. It

may be a good idea to reproduce here any data tables that you completed during the lab.

Data Analysis

Here is where any calculations or graphs are placed. Also show how you arrive at identifying

any unknowns. Make sure that your graphs have titles, labeled axes with units, and legends.

Conclusions

This section is the most important one. Include the following:

Percent error

Sources of error (Don't just say that any errors were the fault of the equipment. Also don't use

the generic excuse that you might have misread the measurements.)

Identify any unknowns

Answer the questions, "What did you learn?"

"Did I accomplish the purpose?"

"How would I improve the experiment next time?"

References

Write down any sources such as your textbook, the Internet, electronic

encyclopedia, books, etc. that you used.

Appendix

Here is where you attach any material that you think is pertinent to the lab report. Also answer

any questions here that are in the lab report. You do not have to re-write the questions, but

label and number them appropriately.

EXPERIMENT 1

CALIBRATION OF VOLUMETRIC GLASSWARE

OBJECTIVES

To calibrate a 10 mL volumetric pipette.

To calibrate a 25 mL volumetric pipette.

To calibrate a 100 mL volumetric flask.

To calibrate a 50 mL measuring cylinder.

INTRODUCTION

Volumetric glassware is marked with and and also

with the temperature at which the calibration applies. For greatest accuracy, volumetric

glassware should be calibrated to measure the volume that is actually contained in or delivered

by a particular piece of glassware. The calibration is done by measuring the mass of water

contained in or delivered by the glassware. The density of water at a particular temperature is

used to convert mass into volume. Pipettes and burettes are calibrated to deliver specific

volumes; whereas, volumetric flasks are calibrated on a to contain basis.

EXPERIMENTAL PROCEDURE

You must use three complete trials for each of the calibration.

1) Calibration of a volumetric pipette ( 10 ml and 25 ml) .

a) Obtain a transfer pipette. If distilled water does not drain uniformly but leaves droplets of water in the inner surface, the pipette should be cleaned. Use a cleaning solution or

detergent to clean the pipette (ask your instructor). Please make sure you have read

(Laboratory techniques) or have been shown the correct way of pipetting by your

instructor.

b) The water used for calibration should be in thermal equilibrium i.e same temperature with the surroundings. The temperature should be recorded at uniform

intervals. Weighing to the nearest milligram will be satisfactory and the use of a top

loading balance is sufficient. Weighing bottles or small conical flasks with a stopper

can be used as containers to hold the calibration liquid.

i. Weigh an empty weighing bottle to the nearest milligram.

ii. Fill the pipette to the mark with distilled water.

iii. Drain the water by gravity (remove pipette bulb or pump) into the weighing bottle and cap the bottle to prevent evaporation.

iv. Weigh the bottle again to find the mass of water delivered from the pipette.

v. Use the following equation to convert mass to volume:

Notes:

Repeat the procedure another 2 times

Perform the above procedure on each of the pipette.

2) Calibration of a volumetric flask (100 ml).

a) Get a 100 mL volumetric flask. Make sure the flask is clean and dry. (Dry the flask by clamping the flask in an inverted position at room temperature if necessary. Do not

dry a volumetric flask in an oven. Very seldom volumetric flasks need to be dried).

Weigh the flask to the nearest milligram.

b) Fill the flask to the mark with distilled water and weigh again.

c) Calculate the mass of water contained in the flask.

d) Convert the mass of water to volume

3) Calibration of a measuring cylinder (50 ml)

Calculate the mass of water contained in the cylinder and convert it to volume

by the procedure you think most appropriate.

True (actual) Volume = (grams of water) x (volume of 1 g of H2O in Table 4.1)

Table 1: Volume occupied by 1.000g of water weighed in air

Temperature,C Volume, mL at ToC

20 1.0028

21 1.0030

22 1.0033

23 1.0035

24 1.0037

25 1.0040

26 1.0043

27 1.0045

28 1.0048

29 1.0051

30 1.0053

31 1.0056

32 1.0058

33 1.0061

Sample Standard Deviation

The standard deviation value represents the average distance of a set of scores from the mean.

It is a statistical measure of the precision for a series of repetitive measurements. The sample

standard deviation, s, is the positive square root of the sample variance.

Where is the sample, is the mean of the sample and N is sample size

RESULTS

A) DATA :

i) 10 mL pipet Trial 1 Trial 2 Trial 3

Mass of container + water (g) :

Mass of container (g) :

Mass of water (g) :

:

Actual volume (mL) :

Average volume (mL) :

Standard deviation, :

Relative standard deviation ( / x ) :

ii) 25 mL pipet Trial 1 Trial 2 Trial 3

Mass of container + water (g) :

Mass of container (g) :

Mass of water (g) :

:

Actual volume (mL) :

Average volume (mL) :

Standard deviation, :

Relative standard deviation ( / x ) :

iii) 100 mL volumetric flask

Trial 1 Trial 2 Trial 3

Mass of flask + water (g) :

Mass of flask (g) :

Mass of water (g) :

C) :

Actual volume (mL) :

Average volume (mL) :

Standard deviation, :

Relative standard deviation ( / x ) :

iv) 50 mL measuring cylinder

Trial 1 Trial 2 Trial 3

Mass of flask + water (g) :

Mass of flask (g) :

Mass of water (g) :

C) :

Actual volume (mL) :

Average volume (mL) :

Standard deviation, :

Relative standard deviation ( / x ) :

[4 x 15 marks]

DISCUSSION

(Hints: Discuss on your findings and relate to your theory and objective of experiment)

[5 marks]

Conclusion

(Hints: Conclusion should contain summary of the results, sum up what you have learned

from the lab. The conclusion should be one paragraph of 5 7 sentences).

[5 marks]

Appendix

Questions

1. Please tell in simplest way what a calibration is.

[4 marks]

2. Draw a flowchart for the calibration of 50 mL measuring cylinder.

[10 marks]

3. With reference to the capacity of the glassware you have chosen, give a set of reading to

illustrate the meaning of good accuracy and poor precision.

.

[5 marks]

4. What does standard deviation, , indicate?

[5 marks]

5. A 50 mL pipet delivers 49.960g of water at 27 0 C. Calculate the volume delivered by

this pipet at 28 0 C (given 1.000g of water weigh in air occupies 1.0048 mL at 28

0 C )

.

[6 marks]

Total Marks = 100

EXPERIMENT 2

EMPIRICAL FORMULAS

OBJECTIVE

To determine the empirical formula of a compound formed by a combination reaction.

INTRODUCTION

The empirical formula of a compound is the formula written with the smallest whole number

ratio of moles of the elements in the compound. The percentage composition of a compound

will enable to obtain the empirical formula. To determine the empirical formula experimentally,

the following is required:

Determine the mass of each element in the compound.

Calculate the number of moles of each element.

Express the ratio of the moles of each element as integers.

For example, when a compound of nitrogen and oxygen is analyzed, it is found that the sample

contains 0.500g N and 1.142g O.

The numbers of moles of these elements are:

0.500g X 1 mol N = 0.0357 mol N ; 1.142g X 1 mol O = 0.0714 mol O

14.0g N 16.0g O

The mole ratio of nitrogen : oxygen is 0.0357 : 0.0714. The mole ratio in integers is 1 : 2

(divide each number by the smaller number i.e 0.0357 = 1 ; 0.0714 = 2 )

0.0357 0.0357

Hence, the empirical formula is NO2. The formula NO2 states that 14.0 g (1mol) of nitrogen

combines with 32.0 g (2 mol) of oxygen to form 46.0 g (1 mol ) of NO2.

In this experiment, a combination reaction of magnesium and oxygen is used to determine the

empirical formula of magnesium oxide. The initial mass of the magnesium and the mass of the

magnesium oxide formed are measured.

MATERIAL AND ME THOD

Chemicals: Mg ribbon

A. Preparation of a clean crucible

1. Take a clean crucible and a lid and check the crucible for any crack or other flaws. If

any is found, request for another one.

2. Place the crucible and lid on a clay triangle and heat with an intense flame for 5minutes.

3. Cool the crucible and lid to room temperature in a desiccator.

4. If the crucible is still dirty, move the whole setup to the fume cardboard and add 1-2

mL

6M HNO3 and gently heat the crucible, evaporate the acid to dryness.

5. Repeat heating with intense flame and subsequent cooling of the crucible.

6. When cool, remove the crucible and lid from the desiccator with tongs and weigh it

with the analytical balance (0.0001g). Record the weight. Do not handle the crucible

with your fingers for the rest of the experiment (so that no dirt is transferred to it).

B. Combination Reaction of Magnesium (Mg) and Oxygen (O)

1. Prepare the sample:

a) Polish about 0.2-0.3 g of magnesium ribbon with steel wool.

b) Weigh the clean magnesium ribbon and record the weight to + 0.0001g. Curl the

ribbon and place it in the crucible.

c) Weigh the crucible, lid and magnesium. Record this weight to + 0.0001 g.

2. Heat the Sample in Air

a) Place the crucible with the magnesium ribbon and lid on the clay triangle

b) Heat slowly and lift the lid occasionally (now and then) to allow access of air to the

magnesium ribbon.

Caution: Rapid oxidation of the Mg will occur if too much air comes in contact with the

Mg and the Mg will burn brightly. If it does, place the lid immediately on the crucible,

allow it too cool and repeat the experiment from Part A.

3. To Complete Reaction

a) Continue heating until there is no change in the appearance of the magnesium ash in

the crucible.

b) Remove the lid. Continue heating the crucible and ash for about 30 seconds.

c) Remove the heat and cool the crucible to room temperature in a desiccator.

d) Take the mass of crucible, ash and lid and record it.

4. Test for Completeness of Reaction

a) Add a few drops of water to decompose any magnesium nitride that may have

formed.

b) Reheat the sample for 1 minute. Allow it to cool and repeat determination of the

mass of the crucible, lid and ash.

c) If this mass is greater than 1% from that recorded in Part B.3; repeat Part B.4.

d) Wash the cool crucible with a dilute solution of 6 M HCl. Discard the solution into

the wash acids container. Rinse with tap water and then with deionised water.

5. Calculations

a) Determine the ratio of the number of moles of magnesium to the number of moles of

oxygen.

b) Determine the formula of the pure compound.

Notes:

You must complete 3 trials of the experiment.

RESULTS

A) DATA:

No Trial 1 Trial 2 Trial 3

1 Mass of crucible + lid (g)

2 Mass of crucible + lid + Mg (g)

3 Mass of crucible + lid + Magnesium oxide:

1st measurement (g)

2nd

measurement (g)

3rd

measurement (g)

4 Mass of magnesium oxide (g)

(3 x 10 Marks)

Calculate the empirical formula of the compound for each trial.

(3 x 10 Marks)

The empirical formula of magnesium oxide: _____________________________

(10 Marks)

DISCUSSION

(Hints: Discuss on your findings and relate to your theory and objective of experiment)

(5 marks)

CONCLUSION

(Hints: Conclusion should contain summary of the results, sum up what you have learned

from the lab. The conclusion should be one paragraph of 5 7 sentences).

(5 marks)

Appendix

Questions

1. What is the difference between an empirical formula and molecular formula?

(5 marks)

2. Draw a flowchart for the determination of empirical formula of magnesium oxide

(10 marks)

3. Write a word equation indicating the process that took place in the above experiment.

(5 marks)

4. A compound consisting of 62.02% C, 13.88% H and 24.10% N has a relative molecular

molecular mass of 116.21. What is the molecular formula?

(10 marks)

Total Marks = 100

EXPERIMENT 3

STANDARDIZATION OF SODIUM HYDROXIDE SOLUTIONS

OBJECTIVES:

To understand the applications of neutralization titration

To standardize a sodium hydroxide solution with potassium hydrogen phthalate

To understand the calculation for titration in order to get the concentration of the standard solution

INTRODUCTION

In volumetric analysis which involves a titration, the volume of reagent needed to react with an

analyte is measured. Increments of the titrant from the burette are added to the analyte solution

until the reaction is complete.

Standardization

The concentration of titrant is known if it is prepared by dissolving a weighed amount of

pure reagent in known volume of solution. This reagent is called a primary standard . It

should be >>99.9% pure and stable when heated. The titrant may not be available as a primary

standard. However, the concentration of the titrant can be determined by titrating it with a

weighed primary standard. This procedure is called standardization and we call the titrant

a standard solution.

In this experiment your solution of NaOH will be standardized by titrating it against a very

pure sample of potassium acid phthalate (KHC8H4O4) of known mass.

NaOH (aq) + KHC8H4O4 (aq) NaKHC8H4O4 (aq) + H2O (l)

Consider the following reaction:

aA + bB product

If V A ml of A with molarity MA, reacts completely with VB ml of B with molarity

MB in the titration, the relationship can be shown as,

MAVA a

--------- = --------

MBVB b

Practically, it is difficult to determine the equivalent point, thus a third substance called

indicator that gives a change when the substance is added with slightly excess quantity is used.

When the change occurs, it is known as the end point. It is not equal to the equivalent point.

The equivalence point occurs when the amount of titrant added is sufficient for a

stoichiometric reaction with analyte. What is actually measured is the end point which there is

change in color of the indicators used in the titration.

Volumetric analysis also can be used to determine the concentration of unknown

solution. It is based on the stoichiometry of the reaction involved. The reaction must rapid

and complete. In this method, a standard solution from the burette is added to a solution

of unknown concentration until the equivalent point is reached. To do this, you will

accurately measure with a burette the volume of your standards base that is required to

exactly neutralize the acid present in unknown.

MATERIALS AND METHODS