Maverick 2

1 Two liquids have the same boiling point and are immiscible. wrich method would you use to try toseparate them?A ChromatographyB Simpte distiilationC Fractional distiltationD Use of a separating funnel.

2 Which mixture can be separated into its componenls by magnetic attraction?A Copper and copper(tl) sutfateB Aluminium and copper(il) sulfateC lron and copperD Copper and aluminium

3 The diagram shows the chromatogram of four different sugars using the same solvent. sucrosehas an Rr value o{ O.24. \Mich sugar is sucrose?

tr--=

oo

oAa"o-'-\

4 Covalent bonds are formed when atoms share electrons. How many blectrons are provided byeach of the atoms of oxygen, fluorine and carbon when they form dvalent compounds?oxvoen fluorine carbon

A1128214c122D222

5 Arnmonia has the structure shown- How many of the etectrons in a molecule of ammonia, NH3 areinvolved in bonding?H_N _H

I

AOHB2C4D6

6 A substance contains the ions x3'and Y2-. vvhat is the simplesl formula of the compoundcontaining the ions X3* and y2-?A X:YZB XYzc XsYD XzYr

2011 Dunman High School preliminary Exam Chemistry paper 1

roiffIl lrwf

5.a. ftE

10

11

12

13

14

which of the following statements best describes the bonding in diamond?A Diamond is made up of positive carbon ions and n"gaiire electrons.B Diamond is made up of carbon atoms joined togethJr by covalent bonds.c Diamond is made up of rings of carbon atoms ,lr"nguo in rayers.D Diamond is rnade up of molecules of carbon.

which of lhe following compounds in a 'l mol/dm3 solution has the lowest pH?A Hydrogen chlorideB Sodium hydroxideC Ethanoic acidD Sodium chloride

Which of the following statements about oxides is true?A Nitrogen dioxide is a neutraloxide.B Zinc oxide dissolves readily in water to form an alkaline solution.C Carbon monoxide will react with aqueous sodium hydroxide to form a salt and waler.D Copper(ll) oxide will react with dilute sulfuric acid to give a blue solution.

Element E bums in orygen to form a white solid which reacls with both dilute hydrochloric acidand aqueous sodium hydroxide. E could beA copperB calciumC aluminiumD magnesium

ln the laboratory, lead(ll) sulfate is best prepared by the reaction betweenA lead(il) oxide and dilute sutfuric acid.B lead(lI) carbonate and dilute sulfuric acid.C lead(ll) hydroxide and aqueous sodium sulfate.D aqueous lead(ll) nitrate and aqueous sodium sulfate.

Aqueous sodium hydroxide forms a coloured precipitate when added to an unknown solution.The precipitate changes colour on standing.which is the likely substance dissolved in the unknown solution?A lron(III) chtorideB lron(lt) sulfateC Lead(II) nitrateD Silver chloride

A solution S forms a white precipitate in both dilute sulfuric acid and acidified silver nitrate solution.What could solution S contain?A Lead(II) chtorideB Bariurn chlorideC Barium nitrateD Sodium chloride

When calcium carbonate is heated, it decomposes acrording to the eguationCaCO3(s) ) CaO(s) + COz(9)

What volume of carbonA 120 dm3B 22Adm3C 240 dm3D 440 dm3

dioxide would be produced if 5009 of calcium carbonate were heated?

2011 Dunman High School preliminary Exam Chemistry paper i

15 Silver ions forms a white precipitate with chloride ions as shown in the equation

10 cm3 or 0.1 mor/dm3 sirver "io"t"

t:r,i;:l; :i5:?; J:,:J,;l 0.1 mor/dm3 or asolution for complete reaction.What is the formula of the chloride?

XzClB XCIC XCl2D XC/3

49.2 g of hydrated rnagnesium sulfate is heated and cooled repeatedly untilmass of 24.a g. Assuming only water of crystallisation is lost when hyJratedheated, what is the formula of the hydrated magnesium sulfate?A MgSOq.HzOB MgSOa.3HzOC MgSOa.SH2OD MgSOa.TH2O

Silver oxide decomposes when heated to give silver and oxygen.2A920(s) ) 4Ag(s) + Oz(g)

55.o g of a sample of silver oxide is heated genlty to conltant mass toresidue. What is the percentage purity of silver oxideiA 22.7 %B 84.7%C 91.Oo/o

D 90.9%

metalX chloride

it reaches a constantmagnesium sulfate is

16

17

18

give 46.6 g of solid

| 9lmple of hydrogen peroxide decomposes in the presence of a metal oxide catalyst.Which of the following statements is TRUE of the reaction?A The total volume of gas produced at the end of the reaction is larger when a more efficient

catalyst is used.B The concentration of hydrogen peroxide lefl in the reaction flask increases with time.C A larger initial gradient of the graph of total volume of gas produced against time is

observed-D Longer time is needed to produce the maximum volume of the gas compared to another

experimental set up that does not contain the metal oxide catalyst.

2011 Dunman High School Preliminary Exam Chemislry paper 1

l9 The following are the data recorded forthree experiments canied out between calcium carbonateand hydrochloric acid.

CaCO3(s) +2HCl(aq) ) CaC/2(aq) + HzO(t) + COz(9)

ExperimentNo.

Mass of CaCO3 / g Volume of HC/ / cm3 Concentration of HC/ /mol/dm3

1.00 25 2.OOil 1.00 50 1.00ill 0.500 25 2.00

From the above data, which of the following graphs shows the relationship among the threeexperiments, Experiment I to Experiment ilt?

o(Jo(l)

E:J5

o()o(l)

Ef6

o()o(l)

EfE

ooooEl6

Experiment I

Experiment lll

time

Experiment lll

time

Experiment I

Experiment ll

time

Experiment ll

Experiment lll

time

2011 Dunman High School preliminary Exam Chemistry paper I

20 The following graph shows how thereaction between hydrochloric acid

total volume of hydrogen produced changes withand excess magnesium.

time for the

1'oo:f,!oo-

IooEf,o

6o

21

22

23

24

timeWhich one of the following statements about the section XY of the graph is conect?A The rate of reaction is decreasing.B The reaction is continuing at a constant rate.C Allthe magnesium has reacted.D No more hydrochloric acid is left in the reaction mixture.

\Mich reaction does not involve the release of energy?A Mixing of aqueous sodium carbonate with hydrochloric acid.B Adding zinc granules to dilute hydrochloric acid.C Reaction of ethanol with oxygen to form carbon dioxide and water.D Formation of oxygen and copper by passing electricity through the aqueous solution of

coppe(lI) sulfate.

\Men sleam is passed over white-hot coke, the temperature of the reaction mixture drops - Twogaseous products are formed in the reaction.Based on the information given,A the reaction between coke and steam is exothermic.B the reaction between coke and steam is endothermic.C an organic compound is formed in the process as well.D water is oxidized in this reaction.

\Mich of the following is not a redox reaction?A CHa + 2Oz ) CO2 + 21119B ZnO + zHCl ) ZnClz + HzOC Mg * CUSOa ) MgSOr + CuD Cu + 4HNO3 ) Cu(NOiz + 2HzO + 2NOz

A student suspected that an unknown colourless solution S contains a reducing agent. To confirmthis, he could

add aqueous iron(Il) choride to s and observe if the solution turns yellow.add aqueous iodine to s and obserye if brown aqueous iodine is decolourised.add acidified aqueous potassium dichromate(Vl) to S and observe if the mixture tumspurple.

D add a few drops of concentrated hydrochloric acid to S and observe if chlorine gas isevolved.

ABC

2011 Dunman High School Preliminary Exam Chemistry Paper 1

25

26

27

28

29

30

It is likely that an element X in Group VII of the periodic TableA forms a hydride of formula XH7.B reacts vigorously with water.C reduces Cr2O72'(aqy to Cdt(aq).D oxidises SO32'(aq) to SOa2'(aq).

Selenium, Se, is in the same group of the periodic Table as sulfur.The formula of calcium selenide isA CaSeB CaSe2C Ca2SeO3D CaSeOo

\l/hy are the elements magnesium and chlorine in the same period of the periodic Table?A Magnesium is a reactive metal and chlorine is a reactive non-metal.B Magnesium and chlorine combine together to form a compound of formula MgC/2.C The atoms of both elements have only three electron shells cnntaining electrons.D The atoms of both elements have eight electrons in their second electron shell.

Which statement about the metal underlined is conect?barium manganese nickel silver

Most reactive Least reactive

A Barium occurs in the Earth's crust as pure barium. but the other rnetals are found ascompounds.

B Manqanese reacts with nickel(ll) oxide upon strong heating.C Nickel reacts with aqueous manganese(ll) chloride.D silver is the only one of the four metals which reacts with cold water.

Which observation will not be made when pieces of sodium were added to aqueous copper(il)sulfate?A Effervescence occuned.B Blue solution tums colourless.C Resulting solution is alkaline.D White precipitate formed.

This question is about the extraction of aluminium from aluminium oxide.

-"("Sari\ c cl.iai\r€

.lhatini.nr ori&7'"-

'rn -rlrtin

Itt:i!'rc (l(t.<1E

Which of these statements is cpnect?A Oxide ions undergo reduction at the anode.B Aluminium oxide is dissolved in walerC Aluminium collects at the cathode.D Electrodes are made of steel.

201 1 Dunman High School Preliminary Exam Chemistry paper 1

Strtta rlumiriorn

31 Three electrochemical cells are sel up using crpper metal and three unknown metals, U. V and Was electrodes, immersed in dilute sulfuric acid of the same concentration.The potential differences between the metals are given in the table below.

Electrochemical cell Metalsused

Voltage / V Positiveelectrode

1 Cu. U -o.45 U2 Cu, V +1.11 Cu3 Cu. W +2.71 Cu

From these results, deduce which of the following conectly list the metals in the order ofincreasing ease of oxidation.A U,V, CU,WB U, Cu,V, WC W,Cu,V,UD W,V, Cu, U

32 ln which of the following set-ups below will the concentration of copper(ll) ions in the electrolyteremain unchanged when electrolysis takes place?

Setuo Electrolvte Positive Electrode Neoative Electrode1 CuSO.(ao) Copoer Coooer2 CuSOo(aq) Coooer Platinum3 CuSor(aQ) Platinum Copper

A 1 onlyB land2onlyC 2and3onlyD 1,2 and 3

33 Why are catalytic crnverters fitted to car exhausts?A To reduce globalwarming.B To improve energy conservation.C To reduce the amount of carbon dioxide emitted.D To reduce the amount of nitrogen oxides emitted.

34 The substances below are present in the exhaust fumes from the chimney of a factory.Which one of these gases cannot be removed by passing the exhaust fumes through aqueoussodium hydroxide and then excess dilute nitric acid?A COzB NHac NzoD SOz

35 To reduce atmospheric pollution, the waste gases from a coal-burning power station are passedth rough powdered calcium carbonate.Which waste gas will not be removed by the powdered calcium carbonate?A Sulfur dioxide, SOzB Nitrogen dioxide, NOzC Carbon monoxide, COD Phosphorus(V) oxide. P2O5

2011 Dunman High School Preliminary Exam Chernistry Paper 1

36

37

38

which equation shows a reaction used to manufacture a solid fertiliser?A CaCO: ) CaO + COzB HNO3 + NHs ) NHqNOsC 2NH4OH + HzSOr + (NH4)zSOq + 2HzOD NH4c/ + NaoH ) Nac/ + Hzo + NH:

which of the following fuels, on combuslion, does nol form a pollutant?A CoalB PetrolC HydrogenD Naturalgas

Fractional distillation can be used to separate crude oil inlo various fractions. \lry5at isorder of the boiling points of the fractions?

Lowest boiling point _----+ Highest boiling pointpetrol kerosene

the correct

ABCD

petrol kerosenebitumen dieselbitumen diesel

HHttH-C_C_H

dieselnaphthanaphthakerosene

HHltH_C-C_H

ttCI CI

lubricating oillubricating oilpetrolpetrol

HHttH-C-C-Ct

ttHCI

39 The diagrams below show the structures of three compounds.

ttCI H

1

Which compounds can be the products of substitution reactions of ethane with chlorine?A 'l and2B 1 and3C 2and3D 1,2and3


40 Condensation polymerisation occurs with the following rnonomers.

HLIF.IH0o\ I _ I / -\\ //-N{€rc-N\ and )cw-c,H',1 ,l'H H-o o-HWhich diagram below represents the structure of a part of the polymer formed?

A o oH HO OHlt ilt til ilt

_C -ffiFC_N-E-N-C-@_C_N_

BOOHHililtt

-c-@-c-o -fl-N-c H,-@-c H,-N -c O OI-l HO OHil ill til flt

-c-@-c-N{ H 2-E-C H'-N -C -@-C-N-

D O HO OH HOil tlt il l ttt

-c-&M_N -c-c H2-t=-c H2-c-N{l-N-C-

END OF PAPER

2011 Dunman High School Preliminary Exam Chemistry paper 1 10

Section AAnswer all the questions in the spaces provided.

This section canies a total of 50 marks.

A1 Six test tubes containing different substances are given below.Test tube A : calcium carbonate and water

Tesl tube B : alcohol and water

Test tube C

Test tube D

Test tube E

Test tube F

sodium chloride and water

ammonium chloride and water

ammonium chloride and sodium chloride

alcohol and sodium chloride

Use the letters given to the test tubes to identify the mixture(s) which can be separated by t3l

(a) filtration

(b) distillation

(c) sublimation

A2 Samples of lead(Il) nitrate and ammonium nitrate were tested in the science laboratories.Both are white solids.

(a) Describe a chemical test lo distinguish between the two chemicals.

(b) Briefly describe how a solution of lead(ll) nitrate can be prepared from common laboratoryreagents in the Science laboratory pl

I2l

22011 Dunman High School Preliminary Exam Chemistry paper 2

A3 An experiment was conducted by adding 0.5 cm3 of sodium hydroxide solution to a testtube containing a salt solution. The height of the precipitate was measured and another0.5 cm3 of sodium hydroxide solution ias aOOeO. The height of the precipitate in the test-tube was plotted against the volume of sodium hydroxide solution added.

height of theprecipitate / mm

V volume of sodium hydroxidesolution added / cm3

State the formula of a possible cation present in the salt solution. t1l(a)

I2l

(b) Using the formula in (a), write an^ionic equation, including state symbols, for the formationof precipitate formed when V cm3 of sodium hydroxide sJlrtion was added.

State the observations as aqueous sodium hydroxide was added to the salt solution until inexcess. t2l

(d) The experiment was repeated with copper(ll) sulfate as the salt solution.Complete the diagram to show the variation of the height of the precipitate as sodiumhydroxide solution was gradually added. t1l


(c)

volume of sodium hydroxidesolution added / cm3

2011 Dunman High School Preliminary Exam Chemistry paper 2

A4 5.0 cm3 of 0.5 molldm3 of sulfuric acid was added from a burette to 25.0 cm3 of sodium hydroxide

solution in a plastic cup. The mixture was stined and the maximum temperature reached wasrecorded. Another 5.0 cm3 of sulfuric acid was added each time. The results of the experimenl

were recorded and a graph was plotted as shown below.

tomperature / +C

28

051015?02530Yolume o( HrSO. added, cmt

(a) What volume of sulfuric acid was required to react completely with 25.0 cm3 of sodium

hydroxide solution?

(b) Calculate the concentration (in mol/dm3) of the sodium hydroxide solution used in the

reaction.

(c) The experiment was repeated with 25.0 cm3 of distilled water added to the 25.0 cm3 of

sodium hydroxide solution in a plastic cup. lt was found that the volume of sulfuric acid used

for complLte neutralisation remained unchanged. Explain why. tll

tl l

12]

2011 Dunman High School Preliminary Exam ChemislryPaper2

A5 A student carried out two experiments to determine how the particle size of magnesium affectsthe rate of reaction between magnesium and hydrochloric acid.Magnesium was present in excess in both the experiments.

(a) State two conditions that should be kept constant for the experiment. I2l

(b) state one method in which the rate of the reaction might be followed.

(c) Given that the rate of the reaction is directly proportional to the concentration ofhydrochloric acid used.Sketch on the axes below, a graph of 1/time versus concentration of hydrochloric acid used

1/time /s'1

concentration of hydrochloric acid(in mot/dm3)

Bromine can be obtained from potassium bromide in the following reaction.

2KBr(aq) + 2HzSOr(aQ) + MnOz(s) ) K2SO4(aq) + MnSOr(aq) * Br2(aq) + 2HzO(t)

(i) Explain. using oxidation states, the reaction that Mno2 has undergone.

tl l

Ao (a)

{21

(ii) Describe the colour change of the reaction mixture of the above reaction.

20ll Dunman High School preliminary Exam Chemistry paper 2

l1l

(b) A sample of aqueous potassium iodide is placed in a test tube. A small quantity ofconcentrated sulfuric acid is added slowly to the aqueous potassium iodide.The colourless solution tums brown.

(i) Explain the property of concentrated sulfuric acid in this reaction with reference tothe colour change.

(ii) Write the ionic equation that shows only the formation of the brown solution. t1l

121

A7 An excess of powdered zinc is added to aqueous copper(Il) surfate.(a) State two observations you would make after rhe reaction is completed. t2l

(b) Explain why the reaction takes place.12)

A6 The table below shows some bond energies.

Bond Bond eneroy /kJ/molH-H 436ct-ct 242H-C/ 431

ln the reaction H2(g) + C/z(9) ) 2HC(g),(a) calculate the enthalpy change, aH, for the formation of 2 motes of hydrogen chloride. t21

201'l Dunman High School preliminary Exam Chemistry paper 2

(b)above reaction. Show the names ofand activation energy for the

{21

A9 Nitrogen and hydrogen are combined together to give ammonia in the Haber process. Theequation for the reaction is

Nz(g)+3H2(g)s 2NH3(g)The table gives the percentage of ammonia in the equilibrium mixture at various temperatures.

Temperatu re fC 7o vield of ammorlia at 250 atm pre=r,rre1000 Neglisible550 15200 B8

(a) ln practice, a temperature of s00 oc is chosen as the operating temperature.Suggesl a reason for not operating the plant at(i) a temperature greater than 500 dC.

(ii) a temperature below S0O "C. t2t

progress of reaction

(ii)

(b) State another condition needed for the Haber process.

2011 Dunman High School preliminary Exam.Chemislry paper2

t1l

A10 Colourless solution of two sodium salts, were electrolysed using carbon electrodes.The followino oroducls were r:ollectedcts were collected-

salt productsaqueous sodium sulfate oxygen and hydroqen

aqueous concentrated sodium chloride chlorine and hvdrooen

(a) Explain the reaction that took place at the cathode when aqueous sodium sulfate waselectrolysed.

I2l

l1I

(b)

(c)

write equation for the reaction at the anode when aqueous sodium sulfate waselectrolysed.

At anode:

Explain how the electrolyte containing aqueous sodium sulfate changes, if any, during theelectrolytic process.

(d) State the change in pH of the electrolyte after aqueous concentrated sodium chloride waselectrolysed for some time. Explain.

I2l

I2l


411 Human activities in recent centuries have released additional amounts of heat absorbing gasesto the atmosphere.Carbon dioxide is a greenhouse gas. Carbon dioxide is given a greenhouse factor of 1.Other gases are given a greenhouse factor that compares their effect with carbon dioxide.The greenhouse effect increases as the factor varue increases.

-. The table gives some information of the five main greenhouse gases.

Greenhouse gas Greenhousefactor

Contribution to theGreenhouse effect /

ollo

Current rate ofincrease in the air /

0lloCarbon dioxide 1 50 0.4

Methane 30 18 1.0Nitrous oxide 160 6 0.3

Ozone 2000 12 1.5Chlorofl uorocarbons (CFCs) 10000 14 2.O

(a) Name the greenhouse gas that is only produced by human activities. t1l

tl l(b) lf equal volumes of each gas were filled in separate gas jars and exposed to sunlight,

which gas jar wilt show the highest rise in temperature? -

(c) suggest why 50% of lhe greenhouse effect is caused by carbon dioxide. t1l

(d) State another major environmental problem causedhuman beings adversely.

by CFCs and explain how it affects

tzl

2011 Dunman High School preliminary Exam Chemislty paper 2

Section BAnswer all three questions from this seclion.

The last question is in the form either/or and only one of the altematives should beThis total mark for this section is 30.

Write your ans\./ers on the 44 papers provided.

812 An ion of erement A has the folrowing erectronic arrangement.

attempted.

Name the particles represented byo and . .

To which group of the periodic Tabre does erement A berong to?

Element A reacts with chlorine gas to form a white crystalline compound. Draw a .dot andcross' diagram to show the bonding in this compound. Show only ihe outer electrons.

It was found that the white orystalline compound formed is able to conduct electricity inmolten form or in aqueous sorution but noi when sorid. gxptain wny.

The chlorine that reacted with element A is a greenish yellow gas at room temperature.Describe the arrangement and movement of the partidls at ro"om temperature.

813 For each of the following reactions,0 state the observations you would expect to make;(!it give the formula of the reaction product(s), and(iii) explain the changes which takes place.

Reaction 1:Chlorine is bubbled into aqueous potassium iodide. The solid product is coltected and thenheated.

Reaction 2:A mixture of copper(ll) oxide and carbon powder is heated strongly over the flame.

(a)

(b)

(c)

(d)

(e)

I2l

t1l

I2l

l3I

{21

rDooo'o oa e o'

t ao o ta

2011 Dunman High School preliminary Exam Chemis try paper 2 10

[10]

CONFIDENTIAL

DUNMAN HIGH SCHOOLzort ruaRx scuerue roR cHerutstRy pRELltvrtNARy EXAM

PAPER 1 I4O MARKSQuestion No 1 2 3 4 5 6 7 I I 10Answer D c A B D D B A D cQuestion No 11 12 13 14 15 16 17 18 19 20Answer D B B A c D D c c DQuestion No 21 22 23 24 25 26 27 28 29 30Answer D B B B D A c B D cQuestion No 31 32 33 34 35 36 37 3B 39 40Answer B B D c c B c A D c

SectlonA(50marksQn AnswerA1 a) A,F

b) B,C, Fc) E

A2 a) Answer A:Add aqueous sodium hvdroxide to separate aqueous samples of two chemicals.

A white precipitate which is soluble in excess aqueous sodium hydroxide showsthat lead(ll) ions are present.Oron warming the mixture without formation of precipitate, a colourless, pungentwhich turned damp red litmus paper blue contains the ammonium salt.

ORAnswer B:Add potassium/sodium iodide solution to separate aqueous samples of twochemicals.The sample which produced a bright yellow precipitate contains lead(ll) ions, the

other sample remains a colourless solution

*must spell 'precipitate" not'ppt" - minus one mark* if 'aqueous samples' not answered, allow ec,f.

b) Add lead(ll) carbonate / lead(ll) oxide/ teaOwarm dilute nitric aciduntilthe lead(ll) compound is in excess.Stir and filter out the excess solid.A solution of lead(ll) nitrate is in the filtrate.

(any 2 points award 1 mark)

A3 a) Zn" / Al'* lPbt'b) Zn" (aq) + 2oH'(aq) ) zn(oH)2 (s)

2011 MARK SCHEME FOR CHEMISTRY PRELIMINARY EXAM

CONFIDENTIAL

Al"(aq) + 3OH-(ad ) Al(OH)s (s)

Pb2.(aq) + zoH-(aq) t Pb(oH)2 (s)

1 mark for balanced equation, I ma* for conect symbols.

c) White precipitate formed

soluble in excess to form a colourless solution

d)


volume of sodium hydroxidesolution added / cm'

A4 a) 20.Ocm'b) HzSOr+2NaOH ) NazSOo +HzO

20.0/1000 dm3 X 0.5 mol/dm3 L225.0/1000 dm'X x moUdmr

concentration (in moUdm3) of NaOH = 0.800 mol/dm3(if missing /wrong units and/or ans not fo 3 srg figure - minus 1 mark)

No.of moles of H2SOa =No.of moleS ofNaOII

c) The volume of sulfuric acid remains unchanged as the number of moles of thesodium hvdroxide solution used in the reaction was the same.


CONFIDENTIAL

A5 a) . Concentration of hydrochloric acid to be kept constant.. Volume of hydrochloric acid to be kept constant.. Temperature of the reaction mixture to be kept constant.1m for each ans Any 2 ans

b) To measure the volume of hydrogen gas coffiOrTo measure the chaqge in mass of the reaction mixture over time

c)

l/time

Concentration ofHCI(mol/dmr)

Note: A Sjlelgh'!]ilggleph that has to pass throuqh the oiiqin;

A6 a) (i) MnOa is reduced to MnSOq.+4 in + MnSO . Hence

MnOz is reduced.(ii) The colourless solution turns reddish brown/brown

b) (i) concentrated sulfuric acid is acting as an oxidisinq aqentas colourless aqueous potassium iodide is oxidised to brown aoueous iodine

(ii) 2l')lz+2e

A7 a) Pink /reddish-brown solid formed.Blue solution turned colourless.Not acceptable - grey solid decreases in amount

b) Zinc is more reactive than copoer. hence zinccoPper.

m aqueous cgpper(ll) sulfate.


CONFIDENTIAL

A8 a) AH = [(+436) + Qa\+ 2x (-431)J kJ= -184 kJ

(if sign is positive, no marks; no units- minus 1 mark)b)

energy

progress of reaction

Hdg) + CIr(g)

Shape: 1m (ecf A6(b) calculation)Labels (reactants & products and Ea and AH= -1MkJ):

lO lg $o be labelled either as 2HCl($ or (c))1m

A9 a) 0 Yield of ammonia decreases at higher temperature.ii) Rate of formation of ammonia will decrease /takes a-lonm

ammonia/ reaction will slow down

b) tqo sq a catalvst for this reaction.

A10 a) Hydrogen ion gains electron more readi[ tnan soOium ionHence hydrogen ion is preferentially discharged to form hydrogen gas.

b) At anode: 4OH'- 4e )2H2O + 02

c) T-he concqntration of H' and OH- iodischarqed to form hydrogen gas and oxygen gasrHence, as the electrolyqis continues, the electrolyte becomes rnore conentrated-

d) pH increases (to above 7)as the chloride ions and hvdroqen ions are preferentiallv discharqed. Hvdroxideand sodium ions are left behind in the electrolyte hence tnisotution Oecornesalkaline.

All a) Chlorofluorocarbonsb) Chlorofluorocarbonsc) Comparing to the other four gases, carb

the air / Concentration of carbon dioxide in the air is higher.d) CFCg depletefthin the ozone laver, altow

sa4h's surface causino diseases such as skin cancer / cataract


812 a) o proton' neutron

b) Group Ic)

lrL\

x- Electron of A0- Electron of Cl

fdeduct 1 mark for inaporopriate size or wrono / missino k

l)ld) The white crystalline solid has an ionic structure / is an ionic compound.

The positive ions of A and the chloride ions are held by stronq electrostaticforces in the solid state.Therefore these ions are not free to move about in the solid state and there isno conduction of electricity.However, in liquid state or aqueous solution, ions are free to move about andcarrv electricitv with them.

e)Gaseous state

Arrangementofmolecules

Molecules are. widely separated I tar aparll very far aparll widely

spaced

. randomly/disorderly/no regular/ no fixed/ haphazard/ disorganized

. arrangemenUpattern/manner

fspread out not accepted]

Movementofmolecules

a

a

Move freely/ move randomly/ move haphazardly/move in all direction

at great speed/ fast speed I raaidlvl ouicklv

CONFIDENTIAL

Section B ( 30 marks )


CONFIDENTIAL

813 Reaction 1:i) Colourless solution turngd brown / reddisn-Orown

Black solid was formed.upon heating the black solid, violet, punqent qa-lra;our evolved.

ii) KC/ and 12

iii) As chlorine is more reactive than iodine und qthan iodine, chlorine Qisplaces iodine from cotourless aqueoui poGssiuiliodide (to form colourless aqueous potassium chloride ina Orown I reOOlsn-brown aqueous iodine).Black iodine crystals sublimed on heatinq to@vaoourReaction 2:

i) Black solid turned reddish-brown.Colourless, odourless qas evolved.

ii) Cu and COz

iii) Carbon, being a reducing agent, @cesbrown copper metal, while ilgelf is oxidised to qa$on dioxide.

Either814 (a) As the molecular mass increases. the boilino po@

This is because as the molecular mamolecular forces of attraction between the molecules alsoincreases-/becomes stronoer. thus more enerqv is needed to overcome thestronger inter-molecular forces of attraction.

814 (b) Anv two of the followinq:

HH HHttttH-C-C:C-C-Htt

HI

H-C-HHIHrllC: C-C-HttHH

HHltH-C _ C_HttH_C - C-Hlr

HHH-

(c) HI

H_C_HHI

Ill-(^_r-_

ult

HHltC-CltHHH

(d) I (i) I Plastic wraps or Plastic clinq films (for wiap


CONFI DENTIAL

(ii)No of carbon atoms = 300 x 2 = 600

OR:814 (a) C4H'OH+60z)4CO2

H HHl.ttC:C-C-C-HrtltHHHH

turns colourless/is decolourised rapidly/immediately.

(b)

(c)

(d)

(e) c4HsoH + Oz ) C3HTCOOHI-H2OOr CaHeOll + Z[OJ + C3HTCOOH +

Conditions required are presence of

HzO

idified um dich ASg*jdiri.,g rou0, und *rr*ino/huu,ino of ,""",ioA is methanolEster : Butyl methanoate

,-oH_d. H H H H\_ | I I I

U_ C _ C _ C_C_HttttH H HH

Organic acids/Carboxylic acids

(0

(h)


Maverick 2

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Transcript of Maverick 2