IGCSE Practice Paper CHEMISTRY PAPER 4 (EXTENDED) 1 hour ...

CHEMISTRY EXTENDED PAPER 4

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IGCSE Practice Paper

CHEMISTRY PAPER 4 (EXTENDED)

1 hour 15 minutes

Answer questions on the Question Paper. Answer all questions. A copy of the Periodic Table is printed on page 13.

The questions in this paper were taken from the following past papers:

Question 1 Question 2 Question 3 Question 4 Question 5 Question 6 Question 7

Cambridge IGCSE Chemistry 0620 Paper 31, Q1, June 2013 Cambridge IGCSE Chemistry 0620 Paper 31, Q2, November 2012 Cambridge IGCSE Chemistry 0620 Paper 31, Q3, November 2012 Cambridge IGCSE Chemistry 0620 Paper 31, Q4, November 2011 Cambridge IGCSE Chemistry 0620 Paper 31, Q5, June 2012 Cambridge IGCSE Chemistry 0620 Paper 31, Q6, November 2011 Cambridge IGCSE Chemistry 0620 Paper 31 Q7, November 2012

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1 Petroleum contains hydrocarbons which are separated by fractional distillation. a i Complete the following defi nition of a hydrocarbon. A hydrocarbon is a compound which

[2] ii Explain what is meant by the term fractional distillation.

[2]

b Some of the fractions obtained from petroleum are given below. State a use for each fraction.

bitumen

lubricating fraction

paraffi n fraction

gasoline fraction

[4]

[Total: 8]

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2 Three of the halogens in Group VII are listed below. chlorine bromine iodine

a i How does their colour change down the Group? [1]

ii How do their melting points and boiling points change down the Group?

[1]

iii Predict the colour and physical state (solid, liquid or gas) of astatine, At.

colour

physical state

[2]

b A radioactive isotope of iodine, 13513I, is used to treat cancer. i Define the term isotope.

[2]

ii How many protons, electrons and neutrons are there in one atom of 13513I?

number of protons

number of electrons

number of neutrons

[2]

iii When this isotope, 13513I, emits radiation, a different element with a proton number of 54 is formed.

What is the name of this element?

[1]

c Fluorine, the most reactive halogen, forms compounds with the other halogens. It forms two compounds with bromine. Deduce their formulae from the following information.

compound 1

The mass of one mole of this compound is 137 g.

Its formula is

[1]

compound 2

0.02 moles of this compound contain 0.02 moles of bromine atoms and

0.1 moles of fl uorine atoms.

Its formula is

[1]

[Total: 11]

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3 The speed (rate) of a chemical reaction depends on a number of factors which include temperature and the presence of a catalyst. a Reaction speed increases as the temperature increases. ii Explain why reaction speed increases with temperature.

[3] ii Reactions involving enzymes do not follow the above pattern.

The following graph shows how the speed of such a reaction varies with temperature.

speed

temperature Suggest an explanation why initially the reaction speed increases then above a certain temperature the speed decreases.

[2] b An organic compound decomposes to give off nitrogen.

C6H5N2Cl (aq) C6H5Cl (l) 1 N2(g) The speed of this reaction can be determined by measuring the volume of nitrogen formed at regular intervals. Typical results are shown in the graph below.

volume of nitrogen

00

time

i The reaction is catalysed by copper. Sketch the graph for the catalysed reaction on the diagram above. [2]

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ii How does the speed of this reaction vary with time? [1]

iii Why does the speed of reaction vary with time?

[2] c Catalytic converters reduce the pollution from motor vehicles.

oxides of nitrogen and carbon monoxide

less harmful gases to atmosphere

catalysts: rhodium, platinum, palladium

ii Describe how carbon monoxide and the oxides of nitrogen are formed in car engines.

[4] iii Describe the reaction(s) inside the catalytic converter which change

these pollutants into less harmful gases. Include at least one equation in your description.

[3] [Total: 17]

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4 Reversible reactions can come to equilibrium. The following are three

examples of types of gaseous equilibria.

A2(g) 1 B2(g) 2AB(g) A2(g) 1 3B2(g) 2AB3(g) 2AB2(g) 2AB(g) 1 B2(g)

reaction 1 reaction 2 reaction 3

a Explain the term equilibrium.

[2]

b The following graphs show how the percentage of products of a reversible reaction at equilibrium could vary with pressure. For each graph, decide whether the percentage of products decreases, increases or stays the same when the pressure is increased, then match each graph to one of the above reactions and give a reason for your choice.

i

% product at equilibrium

00

pressure

effect on percentage of products reaction reason

[3] ii

% product at equilibrium

00

pressure

effect on percentage of products reaction reason

[3]

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iii

% product at equilibrium

00

pressure

effect on percentage of products reaction reason

7

[3] [Total: 11]

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5 Reactive metals tend to have unreactive compounds. The following is part of the reactivity series.

sodium calcium zinc copper silver

most reactive least reactiv

a Sodium hydroxide and sodium carbonate do not decompose when heated. The corresponding calcium compounds do decompose when heated. Complete the following equations.

calcium carbonate

1

Ca(OH)2

1

[2]

b All nitrates decompose when heated.

i The equation for the thermal decomposition of silver(I) nitrate is given below. 2AgNO3 2Ag 1 2NO2 1 O2 What are the products formed when copper(II) nitrate is heated?

[1]

ii Complete the equation for the action of heat on sodium nitrate.

NaNO3

1

[2]

c Which of the metals in the list above have oxides which are not reduced by carbon?

[1]

d Choose from the list above metals whose ions would react with zinc.

[2]

[Total: 8]

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