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A-Level Chemistry Summer Task

i. To provide a bridge from level 2 to level 3 study, and lead into the early

stages of the course

ii. To engage you in independent learning, which is required at level 3

iii. To encourage you to develop your work ethic and commitment to study

iv. To measure your suitability for the course and assess your initial levels of achievement

Useful websites:

Please have a look through the OCR A A-level chemistry specification before starting the course:

https://www.ocr.org.uk/qualifications/as-and-a-level/chemistry-a-h032-h432-from-2015/

This website is also where to go for past paper and mark schemes

Chemguide has good explanations of A-level chemistry concepts:

https://www.chemguide.co.uk/index.html#top

Chemrevise has revision notes for the whole course:

https://chemrevise.org/ocr-revision-guides/

Physics and maths tutor has notes, flashcards and questions for every topic:

https://www.physicsandmathstutor.com/chemistry-revision/a-level-ocr-a/

Machemguy has videos on every topic on our course, he’s also done GCSE videos so it is a good idea to look at some of the topics you found hard this year before starting the course:

https://www.youtube.com/user/MaChemGuy/playlists

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If you need to look answers up that is fine, this is not a test. Please star questions where you

needed to get help. Hand in at your first chemistry lesson. It should take ~1 hour.

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2. (a) Indigestion tablets called antacids can be taken to react with excess hydrochlor ic acid in

the stomach. A student investigated two different antacid tablets labelled X and Y.

Both tablets X and Y, contained calcium carbonate.

(i) Calculate the relative formula mass (Mr) of calcium carbonate, CaCO3.

(Relative atomic masses: Ca = 40, C = 12, O = 16)

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

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

.......................................................................................................................... (2)

(ii) Name the gas formed when calcium carbonate reacts with hydrochloric acid.

.......................................................................................................................... (1)

(b) The student first reacted tablet X and then tablet Y, with 100 cm3 of a hydrochloric acid

solution. The student measured the volume of gas produced during the first five minutes.

The results are shown in the table.

Time in minutes 0 5 1 2 3 4

Volume of gas in cm3

Tablet X 0 48 38 48 48 48

Volume of gas in cm3

Tablet Y 0 72 31 54 67 72

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(i) Draw a graph of the results for tablet Y. (A graph of the results for tablet X has

been drawn for you.)

(3)

(ii) Tablet X contains less calcium carbonate than tablet Y.

How do the results show this?

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

.......................................................................................................................... (1)

(iii) Explain why the rate of reaction slows down for both tablets.

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

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

.......................................................................................................................... (2)

(Total 9 marks)

80

70

60

50

40

30

20

10

0

0 1 2 3 4 5

Tablet XVolume ofgas in cm

Time in minutes

3

4

4

(i) Draw a graph of the results for tablet Y. (A graph of the results for tablet X has

been drawn for you.)

(3)

(ii) Tablet X contains less calcium carbonate than tablet Y.

How do the results show this?

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

.......................................................................................................................... (1)

(iii) Explain why the rate of reaction slows down for both tablets.

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

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

.......................................................................................................................... (2)

(Total 9 marks)

80

70

60

50

40

30

20

10

0

0 1 2 3 4 5

Tablet XVolume ofgas in cm

Time in minutes

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3. Many everyday substances can be classified as acids, bases or salts. For example, car batteries

contain sulphuric acid, oven cleaners contain sodium hydroxide and table salt contains sodium

chloride.

(a) A solution of each of these substances was tested with universal indicator.

Solution Colour of universal indicator

Sulphuric acid (H2SO4) red

Sodium hydroxide (NaOH) purple

Sodium chloride (NaCl) green

Explain how these universal indicator colours and the corresponding pH values

could be used to identify each of these solutions.

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

........................................................................................................................... (3)

(b) Sodium chloride can be made by reacting sodium hydroxide with hydrochloric acid in the

presence of an indicator.

(i) What is the name of this type of reaction?

.......................................................................................................................... (1)

(ii) Write a balanced chemical equation for this reaction.

..............(aq) + ..............(aq) → ..............(aq) + ..............(l) (2)

→

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(c) The atomic number for sodium is 11 and for chlorine is 17.

(i) Complete the diagrams to show the electron arrangements for a sodium atom and a

chlorine atom. (2)

(ii) These atoms form different particles by one electron transferring from the sodium

atom to the chlorine atom. What is the name given to the particles formed?

........................................................................................................................... (1)

(iii) Why do these sodium and chloride particles bond?

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

........................................................................................................................... (1)

(Total 10 marks)

Sodium atom Chlorine atom

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4. Fluorine is a very useful element. It is placed in group 7 of the Periodic Table.

Use your knowledge of the elements in group 7 to help you answer these questions.

(a) Name another element in group 7 of the Periodic Table.

..................................................................................................................................... (1)

(b) Cylinders filled with fluorine molecules are commercially available. What would you

expect the formula of a fluorine molecule to be?

..................................................................................................................................... (1)

(c) Fluoride ions are added to drinking water to help prevent tooth decay. What is the charge

on fluoride ions in the water?

..................................................................................................................................... (1)

(d) Fluorine reacts with the non-metal sulphur to make sulphur hexafluoride (SF6).

(i) What type of bonding would you expect in sulphur hexafluoride?

.......................................................................................................................... (1)

(ii) Explain the reason for your answer to part (i).

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

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

.......................................................................................................................... (1)

(Total 5 marks)

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5. Silicon is an extremely important element. More than a million tonnes of silicon are produced

each year. Silicon is made by reducing silicon oxide (sand) with carbon (coke).

(a) (i) Complete the diagram below to show the arrangement of electrons in an atom of

silicon. The periodic table may help you with this question.

(2)

(ii) Which electrons in the silicon atom take part in chemical reactions with

other atoms?

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

.......................................................................................................................... (1)

(iii) What features of all the atoms of the elements in group 4 of the Periodic Table

might give them similar chemical properties?

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

.......................................................................................................................... (1)

Si

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(b) Silicon is difficult to classify as a metal or a non-metal because it has properties which

resemble both. Some of the properties of silicon are listed below.

• Silicon is a shiny blue/grey solid.

• Silicon is placed in Group 4 of the Periodic Table.

• Silicon has a relative atomic mass of 28.

• Silicon has a very high melting point (1410ºC).

• Silicon has a very high boiling point (2355ºC).

• Silicon conducts electricity.

• Silicon oxide will neutralise alkalis.

• Silicon forms compounds in which the silicon atoms are bonded to other atoms by

covalent bonds.

(i) Select two properties from the list above in which silicon resembles a metal.

1. .....................................................................................................................

2. ..................................................................................................................... (2)

(ii) Select two properties from the list above in which silicon resembles a non-metal.

1. .....................................................................................................................

2. ..................................................................................................................... (2)

(Total 8 marks)

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6. Ammonia is produced by the Haber process. In the process nitrogen and hydrogen are mixed.

The pressure is increased to about 200 atmospheres. The gases are passed over an iron catalyst

at about 450°C. The equation for the reaction is:

N2(g) + 3H2(g) 2NH3(g)

The reaction between nitrogen and hydrogen is reversible. This affects the amount of ammonia

that it is possible to obtain from the process. The graph below shows how the pressure and

temperature affect the percentage of ammonia that can be produced.

Use this information, together with your knowledge of the process, to explain why many

industrial ammonia plants operate at 200 atmospheres and 450°C. Try to consider the

advantages and disadvantages of using higher or lower values for temperature and pressure in

your answer.

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............................................................................................................................................... (Total 5 marks)

4003002001000

10

20

30

40

50

60

70

%ammoniaproduced

pressure (atm)

80

350ºC

400ºC

450ºC

500ºC

550ºC

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7. Use the Periodic Table on the Data Sheet to help you to answer this question.

(a) State one similarity and one difference in the electronic structure of the elements:

(i) across the Period from sodium to argon;

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

........................................................................................................................... (2)

(ii) down Group 7 from fluorine to astatine.

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

........................................................................................................................... (2)

(b) State the trend in reactivity of the Group 1 elements.

........................................................................................................................... (1)

(c) Explain why group 0 elements are unreactive

........................................................................................................................... (1)

(Total 6 marks)

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8 Different isotopes of calcium exist, such as calcium-40 and calcium-44.

(a) Using these as examples explain what you understand by the term isotopes.

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

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

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

(2)

(b) Calcium burns in oxygen in a vigorous reaction. Give a word equation for this process in

the space below.

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

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(2)

(c) Write a balanced symbol equation for reaction of calcium with oxygen.

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

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

(2)

(d) Metal atoms lose outer shell electrons when they react with non-metals. The easier they lose

their electrons the more reactive the metal is.

Given their positions in the Periodic table can you explain why calcium is more reactive than

magnesium?

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(4)

(e) Explain why calcium is malleable.

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(2)

END OF QUESTIONS