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Q1. Mountaineers can warm their food in self-heating, sealed containers. (a) The water is allowed to react with the lime. The heat from the reaction warms the food. What type of reaction causes a rise in temperature? .................................................................................................................................... (1) (b) Some students investigated the effect of adding different sized lumps of lime to water. The results of their investigation are shown. What do these results show? Give an explanation for your answer. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (2) Temperature in °C Time in minutes (^) Large lumps of lime Small lumps of lime Powdered lime 0 18 18 18 1 19 20 28 2 21 23 43 3 24 27 63 4 28 32 88 5 33 38 100
(c) Suggest and explain one disadvantage of using powdered lime to heat food. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (2) (Total 5 marks) Q2. (a) The diagram shows one way of making crystals of copper sulphate. (i) Why was the solution filtered? .......................................................................................................................... (1) (ii) How could you make the crystals form faster from the copper sulphate solution? .......................................................................................................................... (1) (iii) The chemical equation is shown for this reaction. CuO(s) + H 2 SO 4 (aq) → CuSO 4 (aq) + H 2 O(l) In the chemical equation what does (aq) mean? .......................................................................................................................... (1)
(ii) Describe an experiment that the student could do to prove that this reaction is exothermic. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (4) (Total 8 marks) Q4. A student did two experiments using ammonium chloride. (a) In the first experiment the student heated a small amount of ammonium chloride in a test tube. Two reactions take place in the test tube. Reaction 1 ammonium chloride → ammonia + hydrogen chloride (colourless gases) Reaction 2 ammonia + hydrogen chloride → ammonium chloride
(i) Complete the sentences by crossing out the incorrect word in each box. (1) Reaction 1 takes place at a high low temperature. Reaction 2 takes place at a high low temperature. (ii) Draw a ring around the word which best describes reactions 1 and 2. combustion displacement oxidation reduction reversible (1) (iii) Suggest a reason for the mineral wool at the top of the test tube. ........................................................................................................................... ........................................................................................................................... (1) (b) In the second experiment the student mixed a small amount of ammonium chloride with some water in a beaker. The temperature of the water was measured before and after adding the ammonium chloride. Draw a ring around the word which best describes the process which takes place. combustion displacement endothermic exothermic freezing (1) (Total 4 marks) Temperature before adding the ammonium chloride
20°C
Temperature after adding the ammonium chloride
16°C
Q6. Limestone is a useful mineral. Every day, large amounts of limestone are heated in limekilns to produce lime. Lime is used in the manufacture of iron, cement and glass and for neutralising acidic soils. CaCO 3 CaO + CO 2 (i) The decomposition of limestone is a reversible reaction. Explain what this means. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (2) (ii) Calculate the mass of lime, CaO, that would be produced from 250 tonnes of limestone, CaCO 3. Relative atomic masses: C 12; O 16; Ca 40. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... Mass of lime = ........................................ tonnes (3) (Total 5 marks)
Q7. Ammonia and nitric acid are both important chemicals. Nitric acid is made from ammonia. The charts below show substances made from ammonia and nitric acid. Substances made from Substances made from ammonia nitric acid (a) Use the charts to help you answer these questions. (i) What is the main use of both ammonia and nitric acid? .......................................................................................................................... (1) (ii) Work out the percentage of ammonia used to make nitric acid. Percentage = ........................ % (1) (iii) 100 million tonnes of ammonia are made in the world each year. How much of this ammonia is used to make nylon? .......................... million tonnes (1) (b) The word equations below show how nitric acid is made.
- nitrogen + hydrogen → ammonia
- ammonia + oxygen → nitrogen monoxide + water
- nitrogen monoxide + oxygen → nitrogen dioxide
- nitrogen dioxide + water → nitric acid
(c) In the reaction one substance is reduced. (i) Name the substance which is reduced. .......................................................................................................................... (1) (ii) What happens to the substance when it is reduced? .......................................................................................................................... .......................................................................................................................... (1) (Total 5 marks) Q9. (i) Which acid from the list should the student add to sodium hydroxide solution to make sodium sulphate? ethanoic acid hydrochloric acid nitric acid sulphuric acid ..................................................................................................................................... (1) (ii) When the acid was added to the alkali the beaker became warm. Name the type of reaction that releases heat. ..................................................................................................................................... (1) (iii) Use the Data Sheet to help you to write the formula of sodium sulphate. Formula: ..................................................................................................................... (1) (Total 3 marks) Q10. This item appeared in the Wolverhampton Express and Star on October 31st, 1997. Read the passage and answer the questions that follow.
Fumes scare at
factory
Workers were forced to flee a
factory after a chemical alert.
The building was evacuated
when a toxic gas filled the
factory.
It happened when nitric acid
spilled on to the floor and mixed
with magnesium metal powder.
(a) The equation which represents the reaction between magnesium and nitric acid is: Mg(s) + 4HNO3(aq) → Mg(NO 3 )2(aq) + 2H 2 O(1) + 2NO2(g) Give the formula of the toxic gas that was produced. .................................................................................................................................... (1) (b) Explain, in terms of particles, how the toxic gas was able to fill the factory quickly. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (2) (c) The reaction of nitric acid with magnesium metal powder is more dangerous than if the acid had fallen on to the same mass of magnesium bars. Explain why. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (1) (d) (i) Water was sprayed on to the magnesium and nitric acid to slow down the reaction. Explain, in terms of particles, why the reaction would slow down. .......................................................................................................................... .......................................................................................................................... .......................................................................................................................... (2) (ii) Explain why it is better to add alkali, rather than just add water to the spillage. .......................................................................................................................... .......................................................................................................................... (1) (Total 7 marks)
(d) Drops of a clear, colourless liquid formed on the inside of tube B. (i) Name the liquid. ........................................................................................................................... (1) (ii) Explain how the liquid came to be inside tube B. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (e) Anhydrous copper sulphate can be turned into hydrated copper sulphate. What would you need to add? Apart from the change in colour, what could you observe? ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (2) (f) Copper sulphate can be made from black copper oxide by reacting it with an acid. Name the acid. ..................................................................................................................................... (1) (Total 10 marks) Q12. Ammonium nitrate and ammonium sulphate are used as fertilisers.
(i) Which acid reacts with ammonia to form ammonium nitrate? .................................................................................................................................... (1) (ii) Which acid reacts with ammonia to form ammonium sulphate? .................................................................................................................................... (1) (iii) The reactions in (i) and (ii) are both exothermic. How can you tell that a reaction is exothermic? .................................................................................................................................... .................................................................................................................................... (1) (iv) The reactions in (i) and (ii) are both examples of acid + base reactions. What is the name of the chemical change which takes place in every acid + base reaction? .................................................................................................................................... (1) (Total 4 marks) Q13. (a) The equation for the reaction that takes place when ammonium chloride is heated is: NH 4 Cl(s) NH 3 (g) + HCl (g) ammonium chloride ammonia hydrogen chloride The diagram shows how a teacher demonstrated this reaction. The demonstration was carried out in a fume cupboard.
Q14. (a) Iron powder is used in the manufacture of ammonia. Why is it used? ..................................................................................................................................... ..................................................................................................................................... (1) (b) Ammonia is manufactured from nitrogen and hydrogen. The equation for the reaction between them is: N 2 (g) + 3H 2 (g) 2NH 3 (g) (i) Which two raw materials are used to make the hydrogen? .......................................................... and ........................................................ (1) (ii) Why does increasing the pressure increase the chance of molecules of nitrogen reacting with molecules of hydrogen? .......................................................................................................................... .......................................................................................................................... (1) (iii) Calculate the mass, in tonnes, of ammonia which could be produced from 560 tonnes of nitrogen. The relative atomic masses are: H 1; N 14. Show clearly how you get to your answer. .......................................................................................................................... .......................................................................................................................... .......................................................................................................................... Mass of ammonia = ............................................ tonnes (3) (Total 6 marks)
Q15. The diagram shows some magnesium ribbon burning. (a) Choose words from the list to complete the sentences below. electrical heat light kinetic an endothermic an exothermic a neutralisation a reduction When magnesium burns, it transfers ......................................................................... and ............................................................................ energy to the surroundings. We say that it is .................................................................................. reaction. (3) (b) Complete the word equation for the reaction. magnesium + __________________________ magnesium oxide (1) (Total 4 marks)
(e) In an old method, nitrogen monoxide was produced from nitrogen instead of ammonia. The reaction was carried out at a high temperature (3000°C). Suggest two reasons for this. 1 ................................................................................................................................. 2 ................................................................................................................................. (2) (f) Complete the word equation below, to show how to make the fertiliser, ammonium nitrate. ................................... + .............................. ammonium nitrate + water (2) (Total 10 marks) Q17. Instant cold packs are used to treat sports injuries. One type of cold pack has a plastic bag containing water. Inside this bag is a smaller bag containing ammonium nitrate. The outer bag is squeezed so that the inner bag bursts. The pack is shaken and quickly gets very cold as the ammonium nitrate dissolves in the water.
(a) One of the statements in the table is correct. Put a tick ( ) next to the correct statement. (1) Statement ( ) The bag gets cold because heat energy is given out to the surroundings. The bag gets cold because heat energy is taken in from the surroundings. The bag gets cold because plastic is a good insulator. (b) Draw a ring around the word that best describes the change when ammonium nitrate dissolves in water. electrolysis endothermic exothermic (1) (c) Suggest and explain why the pack is shaken after the inner bag has burst. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (2) (Total 4 marks)
