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International GCSE

Centre Number Candidate Number

ChemistryUnit:4CHOScience (Double Award) 4SCOPaper: 1CThursday 17 May 201 8 - MorningTime: 2 hours

Paper Reference4CHO/1C4SCO/1C

You must have:

Calculator, ruler ) Total Marks

Instructions

• Use black ink or ball-point pen.• Fill in the boxes at the top of this page with your name,

centre number and candidate number.

• Answer all questions.• Answer the questions in the spaces provided

- there may be more space than you need.• Show all the steps in any calculations and state the units.• Some questions must be answered with a cross in a box K|. If you change

your mind about an answer, put a line through the box ® and then markyour new answer with a cross g].

Information

• The total mark for this paper is 120.• The marks for each question are shown in brackets

- use this as a guide as to how much time to spend on each question.

Advice

• Read each question carefully before you start to answer it.• Write your answers neatly and in good English.• Try to answer every question.• Check your answers if you have time at the end.

»

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P52322RA©2018 Pearson Education Ltd.

1/1/1/1/1/1/ P52322RA01 36 Pearson

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Answer ALL questions.

1 Chromatography can be used to separate the substances in a mixture.

(a) Diagram 1 shows the apparatus used to separate the different dyes in a food colouring.

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The box lists some terms used in chromatography.

baseline

solvent

chromatography paper

solvent front

Use the terms from the box to label diagram 1 .(3)

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Diagram 2

(i) Which food colouring contains only one dye?

A P

D B Q

^ C R

D S

(ii) Which food colourings have one dye in common?

D A P,QandR

B P, R and S

8 C Q, Rand S

D P,Q, Rand S

(iii) Explain which food colouring contains the largest number of dyes.

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(1)

(1)

(2)

(Total for Question 1=7 marks)

II 5

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2 The diagram shows the apparatus used to prepare carbon dioxide in the laboratory.

dilute hydrochloric acid

calcium carbonate

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gas jar

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(a) What is the name of the piece of apparatus containing the dilute hydrochloric acid?

LJ A burette

D B pipette

Kf C tap funnel

D D thistle funnel

1)

(b) Complete the chemical equation for this reaction.(2)

CaCO, +2^ HCl CaClz + CO, + 1!\UH.O

(c) Which of these is a true statement about carbon dioxide?

D A it turns red litmus blue

S] B it turns limewater milky

C it relights a glowing spill

D it burns with a squeaky pop

(1)

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(d) The diagram shows how carbon dioxide is collected by downward delivery in air.

(i) Give a reason why carbon dioxide can be collected by downward delivery in air.

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(ii) Give another method of collecting carbon dioxide.

.fe$.....&^lh^....(1)

(e) When carbon dioxide dissolves in water, a weakly acidic solution forms.

Suggest a pH value for this solution.(1)

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6.0(f) Carbon dioxide also forms when copper(11) carbonate is decomposed by heating.

The equation for this reaction is

CuC03(s) ^ Cu0(s) + C02(g)

State the change in colour of the solid when copper(11) carbonate decomposes.(2)

from (jl^<\ „ to ...

(g) Suggest two properties of carbon dioxide that make it suitable for use in fire extinguishers.(2$

i.......l0Q^.Ac)hS^^^:.C^t^^t^2. .Ao^c ....c^x. A^ .a<r.,

(Total for Question 2=11 marks)

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3 A teacher investigates the reaction between sodium and water.

The teacher fills a trough with water.

She adds a few drops of litmus solution to the water, and then adds a piece of sodium.

sodiumwater and litmus

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(a) The sodium floats on the water. It reacts with the water and produces bubbles ofhydrogen gas.

(i) State two other observations that are made during the reaction.

So <^^^^^^^^^^^^(2)

.'1^^ J^p^^I

(ii) Balance the equation for the reaction between sodium and water.

Include the state symbols.

rL Na(.....4..,) + .,.Z, H20(.....L.....) -^ .....Z... NaOH(...^.) + .........I...... H^C.....^.

(b) Lithium and potassium react in a similar way to sodium when added to water.

(i) State why they have a similar reaction in terms of the electronic configurationsof their atoms.

?oi^. ....G0.^.h..a/).€.,,^^

(2)

(1)

(1)(ii) Place the elements lithium, potassium and sodium in order of reactivity.

most reactive .....r..P..^>.S.(..tA)^,,,,,,

2.£h:^r\...,..,,....,...,....,...,.,........,..,,...,..,...,...

least reactive ....tdltl.l.<^r(........................................................

(Total for Question 3=6 marks)^

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4 Use the Periodic Table on page 2 to help you answer this question.

(a) Which word correctly describes substances found in the Periodic Table?

a A alloys

D B compounds

^ C elements

D D mixtures

(b) The substances in the Periodic Table are arranged in order of increasing

^ A atomic number

mass number

C nucleon number

D D relative atomic mass

(c) The table lists properties of some of the gases in Group 0 of the Periodic Table.

Gas Symbol Boiling point in K Reaction with metals

helium i He 4 no reaction

27

(1)

(1)

neon M^Arargon

krypton I Kr-I.....

xenon Xe

<b0121

165

no reaction

no reaction

no reaction

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Complete the table by giving

the symbol for neon

an estimate for the boiling point of argon

the reaction of xenon with metals(3)

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(d) The photograph shows an electric light bulb.

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tungsten metalfilament

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The tungsten filament becomes very hot when the light bulb is switched on.

Suggest why argon is a more suitable gas than air to use in the light bulb.(2)

..Ar<^, ^. "1 c&^^^^^^^E<^^^.c Ac^<^ A^ h

f.wfr^.5.......

(Total for Question 4=7 marks)

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5 A student tries to make a pure, dry sample of hydrated cobalt(11) chloride crystals.

He uses dilute hydrochloric acid and solid cobalt(11) oxide.

This is the student's method.

Step 1 pour about 50 cm3 of dilute hydrochloric acid into a beaker

Step 2 warm the acid using a Bunsen burner

Step 3 add a small amount of cobalt(11) oxide and stir the mixture with a glass rod

Step 4 add further small amounts of cobalt(11) oxide until it stops reacting

Step 5 filter the final mixture and collect the filtrate in an evaporating basin

Step 6 leave the filtrate until all of the water has evaporated

His sample of cobalt(11) oxide contains a small amount of a solid impurity thatdissolves in water, but does not react with the acid.

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(a) State why it is not necessary to have a precise measurement of the volume ofhydrochloric acid in step 1.

6£0^3.^.....a^..()^..lh.....^.^

(b) State why the acid is warmed in step 2.

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(1)

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(c) Suggest why a glass rod, rather than a metal spatula, is used to stir the mixture in step 3.(1)

M^.. ..L^C^^ C€^^.....L^.1.^,*-......

(d) State how the student will know when the cobalt(11) oxide stops reacting in step 4.

.^..^.i[L. .&t^.p^... A4^.^p^^'^^.(1)

(e) State why the method used in step 6 will not produce a pure sample of hydratedcobalt(11) chloride crystals.

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(f) Describe how the student could produce a pure, dry sample of crystals from thefiltrate in step 5.

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(g) The table shows the formula and colour of three different types of cobalt(11) chloride.

Formula

CoCl,

Colour

blue

CoClz^HzO

CoCl^^HzO

purple

pinki

When water is added very slowly to solid CoCl;, the colour ofCoCt; changes fromblue to purple and then to pink.

(i) Write a chemical equation for the change from the purple solid to the pink solid.d;

CoC^-^^0 J-^^o^ COCLt.:.6^(ii) Which of these words describes the change taking place when the pink solid

is heated to form the blue solid?

A crystallisation

1^1 B dehydration

D C hydration

D D redox

(Total for Question 5=12 marks)

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6 Tests are done on a sample of a solid, X.

Solid X contains the ammonium ion, NN4, one other cation and one anion.

The table lists details of the tests done on solid X and the observations made for each test.

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V.Observation

Flame test

A sample of solid X is dissolved in deionised water.The solution is divided into three test tubes and thefollowing tests are done:A to the first test tube, add dilute

hydrochloric acidB to the second test tube, add dilute nitric acid

and a few drops of silver nitrate solution

C to the third test tube, add dilutehydrochloric acid and a few drops ofbarium chloride solution

gas given off, gas turns damplitmus paper from red to blue

lilac coloured flame

no observable change

no observable change

white precipitate forms

(a) Identify the gas given off in test 1.

.....NH.^...............................(b) Give the formula of the other cation present in solid X.

.^..__^^^^^^^^^^^^^(c) (i) State what test 3A and test 3B tell you about solid X.

test3A N6.. .<-^b^A(^ 10^^^

test3B AlQ. h^lCl^ t^ ...P/^(ii) Identify the anion in solid X.

L~

(1)

(1)

(2)

(1)

&0^(Total for Question 6=5 marks)

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7 Antimony, Sb, is an element in Group 5 of the Periodic Table.

The mineral, stibnite, contains antimony sulfide, SbzSa

Antimony can be obtained from stibnite in a two-stage process.

Stage 1 stibnite is roasted in air

Sb2S3 + 50; -> SbA + 3502

Stage 2 the oxide produced is heated with carbon to form antimony and carbon dioxide

(a) (i) State why the sulfur in stage 1 is said to be oxidised.

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QoCt^^,,

(ii) Complete the equation for the reaction in stage 2.(1)

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Sb,0,)4 + .....4--... C -^ .......4-.-.. Sb + 2-.co2

(b) Bismuth is another element in Group 5 of the Periodic Table.

Bismuth forms an oxide, Q'bOj, which has a giant ionic structure.

(i) Give the formula of the bismuth ion in bismuth oxide.

(ii) Explain why bismuth oxide has a high melting point.

(1)

(2)

^5}-r^/i^ ^[Qj^nro ^k\~i &f<^5 be-^^^ d)pp^)?.......y.....,,^^,...........^............,....,......................-..................,.,...............^,.........,......................,.,.^

l^^S .(^rlt^ ^kl^O^^CC^/n^.

(ill) Bismuth oxide reacts with dilute hydrochloric acid to form bismuth chloride.

Write a chemical equation for this reaction.(2)

.B>k.tG.s.t...iH^..-^...2^t.a5AJ.rtzP..(Total for Question 7=7 marks)

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I 8 A student investigates the rate of reaction between zinc and hydrochloric acid, usingan excess of zinc powder.

She uses this apparatus.

zinc powder00 0 0

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dilute hydrochloric acid

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The student measures the volume of gas in the syringe every minute for ten minutes.

The table shows her results.

Time in minutes 0 | 1 | 2 | 3

Volume of gas in cm" 0 I 14| 37 |40._L_.__...j_......1_

(a) (i) Plot the student's results on the grid.

(ii) Draw a curve of best fit.

4

49

5 6

54 58

7 8 9

60 60 60

10

60

Volume of gasin cm

18

(2)

(1)

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(b) The result at two minutes is anomalous.

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(i) Suggest a mistake that the student could have made to produce thisanomalous result.

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(ii) Use your graph to estimate the volume of gas that was given off at two minutes.

Show clearly on your graph how you obtain your answer.(2)

volume of gas =.........

(c) Explain why the last four readings for the volume of gas are the same.

z<\

(2)

'Tin ^ f^^h^n i^^; <?iV)iSU b^^^^3-€- aM- 0^"^ ^^ilh^. ..fe.c^^i..

(d) (i) State how the graph shows that the rate of reaction decreases during the firstseven minutes.

13^ ...^^^h 0.c)r.^

(ii) Explain, in terms of the particle collision theory, why the rate of reactiondecreases during the first seven minutes.

^^^ . g^d^^i . 0<|:,^^ ^^^.^........,..§UCL.€^...^.......^^^^^

(1)

(2)

cm3

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(Total for Question 8=11 marks)

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II 9 This apparatus is used to test whether magnesium, solid magnesium chloride and an

aqueous solution of magnesium chloride conduct electricity.

+

lamp

carbon rods

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The table shows the results.

Substance

magnesium

solid magnesium chloride

aqueous solution of magnesium chloride

Conducts electricity

yes

no

yes

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Spl.l.-...^-..^......-.........-,....,^....-.,^[^^.^.f^^......C^l^L^....Con^s^>y:€J-;.... .P.0.6.i})^n,...

)^...,....,^<^^i^..^^^,^.^...^^.... ..,fcn2^....i^..,..m^^.........l/b..^Lh.^..;

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(Total for Question 9=6 marks)

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10 Bromine is a red-brown liquid at room temperature.

Liquid bromine forms a brown gas when warmed.

(a) Explain what happens to the bromine molecules when liquid bromine is warmedto form a gas.

(2)

'l.b^..,.,.,. c?^^6^,.,w^£^^^/ (/

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(b) Bromine reacts with water to form a mixture of hydrobromic acid, HBr, andhypobromous acid, HBrO.

Write a chemical equation for this reaction.

JT^.,0 ^Rgr -h H6r0(1)

z. l2^.^

(c) Hydrobromic acid reacts with magnesium carbonate to form a solution containingmagnesium bromide.

MgC03(s) + 2HBr(aq) -^ MgBr2(aq) + H20(l) + €02(9)

Crystals ofhydrated magnesium bromide, MgBrz^HzO, can be obtained from this solution.

MgBr; + 6^0 -^ N\gB^.6^0

(i) An excess of hydrobromic acid is reacted with 0.125 mol of magnesium carbonate.

Show, by calculation, that the maximum theoretical mass of hydratedmagnesium bromide that can be made is 36.5 g.[M,ofMgBr2.6H20 = 292]

^)rO.I^^A- -'. n^^rJ--0.1?^.L./. nC^6r,-6^^)-o.^S^<

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(ii) In an experiment using 0.125 mol of magnesium carbonate, with an excess ofhydrobromic acid, the mass of hydrated magnesium bromide obtained is 26.4g.

Suggest two reasons why the actual mass obtained is less than the maximumtheoretical mass.

.S.<?L^t?r?.<}..^...l^A.,.,<fc

^5fi^ C^fc^^fe .....(^..i<^P^^

(2)

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(Total for Question 10=8 marks)

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11 Malachite is an ore of copper containing copper(11) carbonate and several other compoundsthat are insoluble in water.

You are supplied with several pieces of malachite, these chemicals and items of apparatus.

Chemicals: dilute sulfuric acid magnesium powder

Apparatus: beakers filter funnel and paper pestle and mortar

Describe how you would use the chemicals and the apparatus to obtain a sample ofcopper from the malachite.

(6)

..Cf^&k 11^ J^^I..^k^.^.^,....t^.^.^J^..fe.l^<li:^....i4^...&o^^^i^<M. ..^^^'^ .^oj^^1^.(^.JI^..L&......(^f^^.....<b^.£?.^^^

(Total for Question 11=6 marks)

I I 25

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12 Crude oil is a mixture of hydrocarbons.

Fractional distillation of crude oil and cracking of hydrocarbon fractions are two ofthe processes used in an oil refinery.

(a) Which property of hydrocarbons is used to separate crude oil into fractions?

^ A boiling point

D B chemical reactivity

D C density

L] D melting point

(1)

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(b) These are the main fractions obtained from crude oil.

bitumen

diesel

fuel oil

gasoline

kerosene

refinery gases

(i) Give one use for the refinery gases.

...c^&^.s:......^^.........................................,....,...........,..,......,.;...(ii) Give one use for kerosene.

\'(AeL Sw o(^w>(iii) State which fraction is the most viscous.

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(c) Catalytic cracking is used to break down long-chain alkanes into shorter-chain alkanesand alkenes.

(i) Name the catalyst used in industrial cracking.

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(ii) State the temperature used in industrial cracking.

(1)

6(1)

606-7oo"C

(iii) Tetradecane (C^Hso) can be cracked to make ethene (C2H4) and only one otherhydrocarbon.

Write a chemical equation for this reaction.

..ci,i/(^-->..a^^.c<AHz&..(iv) Draw the displayed formula of ethene.

(1)

(1)

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(v) Name the polymer formed from ethene.

P^e^onc(vi) Explain why this polymer is difficult to dispose of.

..l3>,.,.10^561 L...cL^.^...fe

(1)

(2)

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(Total for Question 12=11 marks)

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r,j 13 A student investigates the reaction between zinc and dilute sulfuric acid.

I She uses this method.

put 50 cm of dilute sulfuric acid into a polystyrene cup

measure the initial temperature of the acid

add 2.0 g of zinc to the acid and stir the mixture

measure the temperature of the mixture after one minute

The student does the experiment three times. For each experiment, she uses thesame size pieces of zinc but different concentrations of sulfuric acid.

The diagram shows the temperatures for each experiment.

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Experiment 1

1.0mol/dm3H2S04

Experiment 2

1.5mol/dm'H2S04

Experiment 3

2.0mol/dm'H2S04

20 °C

10°C

initialtemperature

20 °C

10°C

initial

temperature

20 °C

10°C

initial

temperature

28

20 °C

10°C

temperature afterone minute

^

30 °C

20 °C

temperature afterone minute

30 °C

20 °C

temperature afterone minute

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(a) Record the temperature readings in the table and calculate the temperature increasefor each experiment.

Give all values to the nearest 0.5 °C.

Initial temperaturein°C

(3)

experiment 1

experiment 2

I experiment 3

Temperature after Temperature increaseone minute in °C in °C

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(b) Explain why the temperature increase changes as the concentration of thesulfuricacid increases.

(2)

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(c) The student does another experiment at the same initial temperature as experiment 3.

She uses the same size pieces of zinc but uses 25 cm of dilute sulfuric acid.

The acid is in excess in both reactions.

(i) Explain the effect, if any, of this change on the initial rate of reaction whencompared to experiment 3.

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(ii) Explain the effect, if any, of this change on the temperature increase whencompared to experiment 3.

(3)

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(Total for Question 13=10 marks)

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14 Iron deficiency anaemia occurs when the body does not have enough iron(11) ions.Iron deficiency can be overcome by taking iron tablets.

A chemist wants to find out the percentage of iron(11) ion (Fe ) in an iron tablet.

She uses this method.

weigh an iron tablet

dissolve the tablet in an excess of dilute sulfuric acid

titrate the solution with potassium permanganate solution, KMn04

The table shows her results.

:!

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mass of iron tablet 0.298 g

!concentration of KMn04 solution 0.0200 mol/dm3

volume of KMn04 solution added | 17.40 cm3

(a) Calculate the amount, in moles,ofKMn04in 17.40 cm3 of 0.0200 mol/dmpotassium permanganate solution.

0.017^0^0.03^0 ^ ^./f^Klo^mo^

f}^GVamount of KMn04 = .....^..'.....

(2)

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(b) In the titration, 1 mol of KMn04 reacts with 5 mol of Fe .

Calculate the amount, in moles, of Fe in the iron tablet.(1)

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(c) Calculate the mass, in grams, of Fe in the iron tablet.[Ar of Fe2+ = 56.0]

|.'74Mo'5>cS6 ~- O.of7^^^_pl ^ n /^^

(1)

mass of Fez+ = g

(d) Calculate the percentage by mass of Fe2+ in the iron tablet.

o_^z-'ft Y too •/. --^z.n-o.zci^

(1)

percentage of Fe = ......o..^:..:..../

(Total for Question 14=5 marks)

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11 33

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15 A teacher uses this apparatus to demonstrate the electrolysis of molten zinc chloride.

lamp!f.

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positive electrode negative electrode

molten zinc chloride

heat

A student records these observations.

crystals of a shiny, grey solid form at one of the electrodes

a pale green substance forms at the other electrode

the lamp goes out after the teacher stops heating the zinc chloride

(a) State what is meant by the term electrolysis.

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(b) State why graphite is more suitable to use for the electrodes than magnesium inthis electrolysis.

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(c) Which of these is a correct statement for this electrolysis?

A the pale green substance is chloride

H B both products are elements

C the pale green substance forms at the negative electrode

D the shiny grey solid is zinc chloride

(d) The student writes this ionic half-equation for the reaction that forms thepale green substance.

2CI- + 2e- -> 2CI

(1)

(2)

Identify the two mistakes in her ionic half-equation.

1.............l^l.^/;^.?............^^........^...^...^.,^

u.....^..a^

(e) The lamp goes out after the teacher stops heating the zinc chloride, becauseelectrons are no longer flowing through the wires.

Explain why electrons are no longer flowing through the wires.

..l^........^Al..........C^n^,A^....A....^...fe.k^..L.........!?.lAC.^.........6'l^..'tl^..

(2)

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(Total for Question 15=8 marks)

TOTAL MARKS FOR PAPER = 120 MARKS

I Ill 35

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Every effort has been made to contact copyright holders to obtain their permission for the use of copyright material.Pearson Education Ltd. will, if notified, be happy to rectify any errors or omissions and include any such rectifications infuture editions.

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