oxford cambridge and rsa gcse (9–1) chemistry a … · oxford cambridge and rsa gcse (9–1 ... 1...

INSTRUCTIONS• Use black ink. You may use an HB pencil for graphs and diagrams.• Complete the boxes above with your name, centre number and candidate number.• Answer all the questions.• Write your answer to each question in the space provided. • Additional paper may be used if required but you must clearly show your candidate

number, centre number and question number(s).• Do not write in the barcodes.

INFORMATION• The total mark for this paper is 90.• The marks for each question are shown in brackets [ ].• Quality of extended responses will be assessed in questions marked with an

asterisk (*). • This document consists of 28 pages.

Turn over© OCR 2017 Practice paperDC (LK/SW) 164464/2

Last name

First name

Candidatenumber

Centrenumber

Oxford Cambridge and RSA

GCSE (9–1) Chemistry A (Gateway Science)J248/04 Paper 4, C4–C6 and C7 (Higher Tier)

Year 11 TestTime allowed: 1 hour 45 minutes

You must have:• a ruler (cm/mm)• the Data Sheet for GCSE Chemistry A

You may use:• a scientific or graphical calculator• an HB pencil

OCR is an exempt Charity

H

2

J248/04© OCR 2017 Practice paper

SECTION A

Answer all the questions.

You should spend a maximum of 30 minutes on this section.

1 Look at the equation for the reaction between copper oxide, CuO, and hydrochloric acid, HCl.

CuO + 2HCl → CuCl 2 + H2O

A student reacts 7.95 g of copper oxide with hydrochloric acid.

The student predicts she should make 13.45 g of copper chloride, CuCl2.

She actually makes 11.00 g.

What is her percentage yield?

A 30.8%

B 59.1%

C 72.3%

D 81.8%

Your answer [1]

3

J248/04 Turn over© OCR 2017 Practice paper

2 Look at the graph.

It shows the percentage of ammonia made under different conditions of temperature and pressure.

70

60

50

40

30

20

10

1000 200Pressure (atmospheres)

Percentageof

ammoniamade

300 400

350 °C

450 °C

550 °C

Predict the percentage of ammonia made at 500 °C and 350 atmospheres?

A 20%

B 30%

C 40%

D 70%

Your answer [1]

3 Raw liver can act as a catalyst. It speeds up the decomposition of hydrogen peroxide.

Why does raw liver act as a catalyst in this reaction?

A Liver contains an enzyme called catalase.

B Liver increases the activation energy of the reaction.

C Liver increases the concentration of the hydrogen peroxide.

D Liver reduces the frequency of successful collisions in the reaction.

Your answer [1]

4


4 Magnesium metal reacts with hydrochloric acid.

Which concentration of hydrochloric acid will give the fastest rate of reaction?

A 1.0 × 10–2 mol / dm3

B 2.5 × 10–4 mol / dm3

C 5.0 × 10–2 mol / dm3

D 7.5 × 10–3 mol / dm3

Your answer [1]

5 What is the general formula for the alkanes?

A CnH2n

B C2nHn

C C2n+2Hn

D CnH2n+2

Your answer [1]

6 Look at the displayed formula for propene.

H

H

C

H

C

H

H

C H

Poly(propene) is a polymer made from propene.

H

H n

C

H

H

A B C D

C

H

n

C

H

H

C

H

H

C

H

CH3n

C

H

H

C

H

CH3n

C

H

H

C

Which is the displayed formula for poly(propene)?

Your answer [1]

5


7 A student investigates the reaction between 1 g of zinc metal and 50 cm3 of dilute sulfuric acid.

Hydrogen gas is given off in the reaction and a colourless solution is made.

50 cm3 of hydrogen gas is collected in 65 seconds.

The student wants to make the reaction go faster by adding a catalyst. She investigates four possible substances to use as a catalyst.

Substance Appearance of substance at start

Time to collect 50 cm3

of hydrogen(s)

Other observations

A blue solid 10 zinc is coated with a pink solid

B green solid 15 zinc is coated with a grey solid

C red-brown solid 56 red-brown solid left behind

D white solid 65 white solid left behind

Which substance is a catalysts?

Your answer [1]

8 A titration is used to find out the concentration of an acid or an alkali.

The titration is repeated until two concordant titres are obtained.

What is meant by concordant titres?

A The final burette readings are identical to each other.

B The final burette readings are within 0.10 cm3 of each other.

C The volumes added from the burette are within 0.10 cm3 of each other.

D The volumes added from the pipette are within 0.10 cm3 of each other.

Your answer [1]

6


9 How many moles of oxygen are in 200 cm3 of oxygen gas at room temperature and pressure?

Use 1 mole = 24 dm3 of gas.

A 8.3 × 10–5

B 8.3 × 10–3

C 8.3 × 10–2

D 8.3

Your answer [1]

10 Chemical engineers consider many factors when choosing a reaction pathway.

Which of the following would they consider?

A Physical properties of the raw materials

B pH of the product

C Rate of reaction

D Reactivity of the product

Your answer [1]

11 Which of the following describes condensation polymerisation?

A Many monomer molecules join together to form a polymer molecule.

B Many monomer molecules join together to form a polymer molecule and water molecules.

C Many molecules react together to form a polymer molecule and carbon dioxide molecules.

D Two molecules react together to form a polymer molecule.

Your answer [1]

7


12 1.20 g of copper(II) sulfate was dissolved in 500 cm3 of water.

What is the concentration of the copper(II) sulfate solution in g / dm3?

A 0.0024 g / dm3

B 0.6 g / dm3

C 2.4 g / dm3

D 600 g / dm3

Your answer [1]

13 Look at the equation for a reversible reaction.

N2(g) + 3H2(g) 2NH3(g) ΔH = –92 kJ / mol

In a sealed container the reversible reaction forms a dynamic equilibrium.

Which changes will move the position of equilibrium to the right?

A Decreasing the pressure and decreasing the temperature.

B Decreasing the pressure and increasing the temperature.

C Increasing the pressure and decreasing the temperature.

D Increasing the pressure and increasing the temperature.

Your answer [1]

14 Why is chlorine more reactive than iodine?

A The outer shell of a chlorine atom is closer to the nucleus and an electron is gained more easily than iodine.

B The outer shell of a chlorine atom is closer to the nucleus and an electron is lost more easily than iodine.

C The outer shell of a chlorine atom is further from the nucleus and an electron is gained more easily than iodine.

D The outer shell of a chlorine atom is further from the nucleus and an electron is lost more easily than iodine.

Your answer [1]

8


15 Polyesters are polymers.

They are made when two different monomers react.

Which functional groups do these monomers contain?

A –COOH and –OH

B –CONH2 and –COOH

C –CONH2 and –OH

D –NH2 and –COOH

Your answer [1]

9


SECTION B

Answer all the questions.

16 A student investigates the reaction between calcium carbonate, CaCO3, and hydrochloric acid, HCl.

(a) Write the balanced symbol equation for this reaction.

.............................................................................................................................................. [2]

(b) The student wants to investigate how changing the size of the marble chips (calcium carbonate) affects the rate of the reaction.

Dilute hydrochloric acid

Balance

Beaker

Marblechips

The student does the experiment using 20 g of small marble chips and 50 cm3 of dilute hydrochloric acid.

The student:

• Adds 50 cm3 of dilute hydrochloric acid to the conical flask• Places the flask on the balance• Sets the balance to zero and adds 20 g of small marble chips into the acid• Starts a stop clock• Records the loss in mass every 30 seconds for 5 minutes.

The temperature of the acid is 20 °C.

The student repeats the experiment using 20 g of large marble chips.

(i) Write about two ways the student could improve her experiment.

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [2]

(ii) The rate of reaction is faster with small marble chips.

Explain why.

...................................................................................................................................... [1]

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(c) Another student investigates the reaction between marble chips and hydrochloric acid.

He uses the same method. Look at the graph of his results.

00.0

0.1

0.2

0.3

Loss inmass

(g)

0.4

0.5

0.6

50 100 150Time (seconds)

200 250 300 350

(i) The student knows that the reaction is still taking place after 50 seconds.

Explain how he can tell this from his results.

...................................................................................................................................... [1]

(ii) How long does it take for this reaction to stop?

Answer = ............................................. seconds [1]

(iii) Use the graph to calculate the mean rate of reaction between 50 seconds and 100 seconds.

Answer = ........................................ units ........................................ [3]

11


(iv) The student repeats his experiment. This time he uses hydrochloric acid which is at a higher temperature.

The reaction is faster.

Explain why. Use ideas about collisions between particles.

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [2]

12


17 Ammonia is used to make fertilisers.

Fertilisers provide three of the essential elements needed by plants:

• Nitrogen• Phosphorus • Potassium.

(a) Plants do not grow well if these essential elements are in limited supply in the soil.

The plants may show signs of mineral deficiency.

Complete the table.

Element Problem caused by mineral deficiency

Nitrogen, N ....................................................................................

Phosphorus, P Poor root growth, discoloured leaves

Potassium, K ....................................................................................

[2]

(b) Ammonia, NH3, reacts with nitric acid, HNO3, to make ammonium nitrate, NH4NO3.

The equation for the reaction is:

NH3 + HNO3 → NH4NO3

Calculate the mass of ammonium nitrate which could be made from 51 tonnes of ammonia.

Answer = .............................................. tonnes [2]

13


(c) Ammonium nitrate can also be made from ammonium chloride.

Ammonium chloride + Silver nitrate → Ammonium nitrate + Silver chloride

NH4Cl + AgNO3 → NH4NO3 + AgCl

Substance Relative formula mass, Mr

NH4Cl 53.5

AgNO3 169.9

NH4NO3 80.0

AgCl 143.4

Silver chloride is a waste product in this reaction.

Calculate the atom economy for this reaction.

Answer = ....................................................... % [2]

14


18 An instrument called an infrared spectrometer can detect covalent bonds in a molecule.

It measures the ‘wavenumber’ of different bonds and shows this in an infrared spectrum.

Look at the infrared spectrum for compound X.

40000

20

40

60% Transmittance

Wavenumber (cm–1)

80

100

3500 3000 2500 2000 1500 1000

1282

890

3357 2975

The table shows the ‘wavenumber’ for different bonds in an infrared spectrum.

Bond Wavenumber (cm–1)

C–H 2850–3300

C–C 750–1100

C=C 1620–1680

C=O 1680–1750

C–O 1000–1300

N–H 3360–3500

O–H 3230–3550

(a) Compound X has a relative formula mass, Mr , of 60.

Use the infrared spectrum and the relative formula mass, Mr , to complete the displayed formula for a molecule of compound X.

C C C

[2]

15


(b) A different compound, Y, also has a relative formula mass, Mr , of 60.

Here is the mass spectrum for nitrogen.

Relative abundance

Mass to charge ratio

100

80

60

40

20

0.012 16 20 24 28 32

Molecular ion peak

Look at the mass spectrum for compound Y.

0.00.0

20

40Relative abundance

60

80

100

10 20 30 40Mass to charge ratio

50 60 70

A

B C

Which peak, A, B or C, on the mass spectrum represents the molecular ion peak of compound Y?

Explain your answer.

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [2]

16


(c) Compound Y is a carboxylic acid.

Propanoic acid, C2H5COOH, is also a carboxylic acid.

(i) Draw the functional group in propanoic acid.

...................................................................................................................................... [1]

(ii) Propanoic acid reacts with sodium carbonate, Na2CO3.

Sodium propanoate, C2H5COONa, and two other products are made.

Write the balanced symbol equation for this reaction.

...................................................................................................................................... [2]

17


19 The Group 1 elements are known as the alkali metals.

The table shows some information about five elements in Group 1.

The properties of rubidium are missing from the table.

Element Symbol Melting point (°C)

Boiling point (°C)

Density (g/cm³)

Lithium Li 181 1342 0.53

Sodium Na 98 883 0.97

Potassium K 64 759 0.89

Rubidium Rb ....................... ....................... .......................

Caesium Cs 29 671 1.87

(a) Look at the properties of the elements.

(i) Which one of the properties of the elements does not show a definite trend?

...................................................................................................................................... [1]

(ii) Predict values for the three properties of rubidium that are missing.

Write your answers in the table. [3]

(b) (i) Lithium reacts with water.

Lithium hydroxide and hydrogen are made.

Write the balanced symbol equation for the reaction.

...................................................................................................................................... [2]

(ii) Which reacts faster with water, lithium or rubidium?

Explain your answer. Use ideas about electrons.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [3]

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20 A school has a fence made of galvanised steel. Galvanised steel is steel coated with a layer of zinc.

(a) Explain why galvanised steel does not rust.

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [2]

(b) Carbon steels are alloys made of iron and carbon.

Look at the table.

Carbon steelPercentage of carbon

(%)Relative

tensile strength Relative ductility

A 0.10 1.00 1.00

B 0.20 1.17 0.89

C 0.27 1.23 0.82

Describe the trend in relative tensile strength.

...................................................................................................................................................

.............................................................................................................................................. [1]

19


21 This question is about the Earth and its atmosphere.

(a) There are many ideas about the formation of the Earth’s atmosphere.

It is likely that in the formation of the Earth’s atmosphere volcanoes released huge amounts of water vapour and carbon dioxide.

Describe how scientists think an oxygen-rich atmosphere developed over time.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [3]

20


(b) The graphs show changes in the Earth’s atmosphere between the years 1850 and 2010.

They show

• the changes in mean temperature of the Earth’s atmosphere• the changes in relative amount of carbon dioxide in the Earth’s atmosphere.

–0.61850 1870 1890 1910 1930

Year

1950 1970 1990 2010

–0.4

–0.2

0.6

0.4

0.2

Change intemperature

(°C)0.0

Relativeamount of

carbon dioxide

1850 1870 1890 1910 1930Year

1950 1970 1990 2010

Carbon dioxide from burning fossil fuelsKey

Carbon dioxide from changes in land useTotal amount of carbon dioxide in the atmosphere

21


Some scientists think there is a link between the amount of carbon dioxide in the atmosphere and the temperature of the atmosphere.

Evaluate to what extent the graphs show that carbon dioxide levels are linked to global temperatures.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [3]

(c) Describe the enhanced greenhouse effect and the problems it may cause.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [4]

22


22 A student does a titration using sulfuric acid and sodium hydroxide.

0.10 mol / dm3 sulfuric acid

Burette

25.0 cm3 of 0.10 mol / dm3 sodium hydroxideand a few drops of indicator

The student does a rough titration to find the approximate volume (titre) of sulfuric acid needed to neutralise the sodium hydroxide solution.

(a) Describe how she uses the same equipment to obtain a repeatable titre for the volume of sulfuric acid needed to neutralise the sodium hydroxide.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

.............................................................................................................................................. [3]

(b) The table shows the colours of some indicators that could be used in the titration.

Indicator Colour in acid Colour in alkali Colour at end point

Litmus Red Blue Purple

Phenolphthalein Colourless Red Colourless

Bromothymol blue Yellow Blue Green

Litmus is not a good choice of indicator for this titration.

Suggest why.

...................................................................................................................................................

.............................................................................................................................................. [1]

23


(c) The student recorded the following results.

Titration number 1 2 3 4

Final burette reading (cm3) 26.85 26.15 26.90 24.95

Initial burette reading (cm3) 1.75 2.85 3.65 1.65

Titre (volume of acid used) (cm3) 25.10 23.30 23.25 23.30

(i) Which results should the student use to calculate the mean volume of acid used?

Explain your choice.

...........................................................................................................................................

...................................................................................................................................... [2]

(ii) Calculate the mean volume of acid used from the results.

Give your answer to 2 decimal places.

Answer = .............................................. [1]

(d) Another student found that 25.0 cm3 of sodium hydroxide was neutralised by exactly 22.30 cm3 of 0.10 mol / dm3 sulfuric acid.

Look at the equation for the reaction between sulfuric acid, H2SO4, and sodium hydroxide, NaOH.

H2SO4 + 2NaOH → Na2SO4 + 2H2O

Calculate the concentration of sodium hydroxide in mol/dm³.

Give your answer to 2 significant figures.

Answer = ..................................... mol / dm3 [4]

24


23 This question is about biological methods of metal extraction.

High-grade ores, which are rich in copper, are running out.

Research is being carried out to find new ways to extract copper from the remaining low-grade ores without harming the environment too much.

(a) (i) Bioleaching is one method of extraction being used. Bioleaching extracts copper from copper ores using bacteria.

Write about the advantages and disadvantages of bioleaching compared to traditional mining and purification of copper.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [4]

(ii) During bioleaching, iron(II) ions are oxidised to iron(III) ions.

Explain, with the help of a balanced ionic equation, why this is oxidation.

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [2]

(b) Phytoextraction is another method of extraction being used.

(i) Describe how plants are used in phytoextraction to extract metals.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [3]

(ii) Phytoextraction is a more carbon-neutral activity than traditional mining and processing.

Explain why.

...........................................................................................................................................

...........................................................................................................................................

...................................................................................................................................... [2]

25


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26


24* In the chemical industry methanol, CH3OH, is made by reacting carbon monoxide and hydrogen.

Look at the equation for the reaction.

CO(g) + 2H2(g) CH3OH(g)

The reaction is reversible. The forward reaction is exothermic.

The table shows the percentage of methanol made at different temperatures and pressures.

Pressure (atmospheres)

Percentage of methanol (%)

At 275 °C At 300 °C At 325 °C At 350 °C

25 14 6

50 39 27 10

70 54 35 20 10

150 82 69 53 36

300 96 90 82 70

The conditions used to make methanol in the chemical industry are

• 50–100 atmospheres pressure • 300 °C• A catalyst.

27


Analyse the data in the table to describe and explain the conditions which would give the maximum yield of methanol.

Explain why the actual conditions used in the chemical industry are different.

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END OF QUESTION PAPER

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