Y10 ChemistryDouble Award Science and Separate Science Chemistry

Practice Examination

NAME: ………………………………………………………. Science Group: ………….

There are a total of 62 marks in this exam

Notice for Double Award Students

Double Award students are not expected to revise “Quantitative Chemistry” and “Rates of Reaction” at this stage so there is no need to answer questions 8a, 9 and 10. Therefore, the total number of marks for Double Award students is 44 marks

Approximate grade boundaries:

A* = 80% A = 70% B = 60% C = 45% D = 38%

Instructions

Use blue or black ink Read the question through carefully before beginning your response You are reminded to use good English and clear sentence structure Show all your working in calculations

Q1.          The table shows the % composition by mass of modern British coins. 

COIN % COMPOSITION BY MASS

copper nickel tin zinc

£1 70 5.5 – 24.5

20p 84 16 – –

5p, 10p, & 50p  75 25  –  –

1p &2p (until 1991)

97 – 0.5 2.5

1p &2p (1992 onwards)

Copper plated steel

(a)     Shade the pie chart to represent the % of copper in a £1 coin.

(1)(b)     Name the metal present in:

(i)      all these coins,

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(ii)     a £1 coin but not in a 20p coin.

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(c)     The following is a list of properties.

•        bends easily

•        good conductor of electricity

•        hard

•        high melting point

•        poor conductor of heat

•        unreactive

         From this list, choose two properties which coinage metals should have.  For each property, give a reason for your answer.

Property 1 ...................................................................................................................

Reason ........................................................................................................................

Property 2 ...................................................................................................................

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

(Total 5 marks)

 

Q2.          A student was trying to extract the metals from lead oxide and aluminium oxide.

          She heated each oxide with carbon in a fume cupboard as shown below.

          She was able to extract lead from lead oxide but not aluminium from aluminium oxide.

(i)      Explain the results of these experiments.

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(ii)      Complete this word equation for the reaction between lead oxide and carbon.

lead oxide + carbon → .................................... + ....................................... (2)

(Total 5 marks)

3(a)     The diagram represents an atom of nitrogen.

Label the diagram.

(3)

(b)     Ammonia has the formula NH3. It is made from nitrogen and hydrogen.

How many atoms are in an ammonia molecule? ..........................................(1)

(c)     The diagrams show the electron arrangement in nitrogen and hydrogen.

                                        

                                   Nitrogen                             Hydrogen

Which diagram below, A, B, C or D, represents an ammonia molecule?

A                                     B                                      C                                     D

Write your answer in the box.

Diagram (1)

(Total 5 marks)

 

Q4.          Read the information in the box and then answer the question. 

Aluminium is made by the electrolysis of aluminium oxide.

Aluminium oxide is an ionic compound containing aluminium ions (Al3+) and oxide ions (O2–).

The diagram below shows the apparatus used to electrolyse aluminium oxide.

(a)     In this question you will get marks on using good English, organising information clearly and using specialist terms correctly.

Use information in the box and your knowledge and understanding of this process to answer this question.

Explain, as fully as you can, how aluminium and carbon dioxide are formed in this process.

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(b)     Aluminium is a metal.

Explain why aluminium conducts electricity.

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(Total 8 marks)

Q5.   This question is about oxygen atoms. The periodic table on the Data Sheet may help you to answer this question.

(a)     (i)      Oxygen atoms have 8 electrons.

         Complete the diagram to represent the arrangement of electrons in an oxygen atom.Use crosses (×) to represent the electrons.

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(ii)     Name the part of the oxygen atom that is labelled A on the diagram.

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(b)     Two isotopes of oxygen are oxygen-16 and oxygen-18.

16                                  18     O                            O

              8                                    8

                oxygen-16                     oxygen-18

                                                               

         Explain, in terms of particles, how the nucleus of an oxygen-18 atom is different from the nucleus of an oxygen-16 atom.

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(Total 4 marks)

Q6. The salt sodium hydrogen phosphate (Na2HPO4) is used as a softening agent in processed cheese.

It can be made by reacting phosphoric acid (H3PO4) with an alkali.

(a) Complete the name of an alkali that could react with phosphoric acid to make sodium hydrogen phosphate.

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(b) What is the name given to a reaction in which an acid reacts with an alkali to make a salt?

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(c) How would the pH change when alkali is added to the phosphoric acid solution?

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(d) What ions are present when any acid is dissolved in water?

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(e) What ions are present when any alkali is dissolved in water?

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(f) Write a chemical equation for the reaction which takes place between the ions you have named in (e) and (f).

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(Total 6 marks)

Q7. The following passage is about the preparation of lead iodide, an insoluble salt.

An excess of potassium iodide in solution was shaken with some lead nitrate solution in a test tube.

The lead iodide precipitate was separated from the mixture and then washed several times with water.

The lead iodide was dried and then placed in a bottle.

(a) Suggest a reason why excess potassium iodide was used.

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(b) What word used in the passage shows that lead iodide is insoluble?

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(c) Suggest how lead iodide can be separated from the mixture.

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(d) Why was the lead iodide washed with water?

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(e) Suggest a method which could be used to dry this lead iodide.

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(f) Lead compounds are toxic.

Suggest a suitable safety precaution that should be taken when using toxic substances in laboratories.

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(Total 6 marks)

Q8. Double Award students go straight to part (b) - although you will have to know this eventually!

Perfumes contain a mixture of chemicals.

                                                                       

          The main ingredients of perfumes are a solvent and a mixture of fragrances.

(a)     A sample of the solvent used in one perfume contained 0.60 g of carbon, 0.15 g of hydrogen and 0.40 g of oxygen.

          Relative atomic masses: H = l; C = 12; O = 16.

          Calculate the empirical (simplest) formula of the solvent.

          You must show all of your working to gain full marks for this question.

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(b)   Solvent molecules evaporate easily.

          Explain why substances made of simple molecules evaporate easily.

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(2)

(c)     Most companies claim that their perfumes have been tested on skin. A study was made of the tests they used. The study found that each company used different tests.

          The perfumes were tested in the companies’ own laboratories and not by independent scientists.

          Some companies did not give any information about the tests that they had used.

(i)      Suggest why companies test their perfumes on skin.

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(ii)     Did the study show that the tests made by the different companies were valid and reliable?

         Explain your answer.

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(Total 9 marks)

 

Q9.          <Triple Award Students only> Aspirin tablets have important medical uses.

(a)     Aspirin is made when salicylic acid reacts with ethanoic anhydride.

The equation for this reaction is:

       C7H6O3      +      C4H6O3      →      C9H8O4      +      CH3COOH    salicylic acid                                  aspirin

Calculate the maximum mass of aspirin that could be made from 100 g of salicylic acid.

Show clearly how you work out your answer.

The relative formula mass (Mr) of salicylic acid (C7H6O3) is 138.The relative formula mass (Mr) of aspirin (C9H8O4) is 180.

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Maximum mass of aspirin = .................................... g(2)

(b)     (i)      In an experiment a chemist calculated that the maximum yield of aspirin is 400 g.

The chemist did the experiment but only made 250 g of aspirin.

Calculate the percentage yield of aspirin for this experiment.

Show clearly how you work out your answer.

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Percentage yield of aspirin = ........................... %(2)

(ii)     Suggest one possible reason why the chemist did not have a percentage yield of 100%.

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(c)     The use of a catalyst might reduce costs in the industrial production of aspirin.

Suggest how (Double Award students don’t have to answer this question yet).

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(Total 6 marks)

Q10.    <Triple Award Students only> A student investigated the rate of reaction between marble and hydrochloric acid.

The student used an excess of marble.

The reaction can be represented by this equation.

CaCO3 (s)   +   2HCl (aq)   →   CaCl2 (aq)   +   H2O (l)   +   CO2 (g)

The student used the apparatus shown in the diagram.

The student measured the mass of the flask and contents every half minute for ten minutes.

The results are shown on the graph. Use the graph to answer the questions.

(a)     Complete the graph opposite by drawing a line of best fit.(1)

(b)     Why did the mass of the flask and contents decrease with time?

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(1)

(c)     After how many minutes had all the acid been used up?

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(d)     The student repeated the experiment at a higher temperature. All other variables were kept the same as in the first experiment. The rate of reaction was much faster.

(i)      Draw a line on the graph to show what the results for this second experiment might look like.

(2)

(ii)     Why does an increase in temperature increase the rate of reaction?

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(Total 8 marks)