1. a) One of the least abundant gases in the atmosphere is
(1)
b) A gas which pops when ignited in air is
carbon dioxide hydrogen nitrogen oxygen
(1)
c) Some substances do not change chemically when heated. An example of such a substance is
copper carbonate hydrated copper sulphate magnesium oxide potassium manganate(VII)
(1)
d) A solution of copper sulphate forms crystals when left on a window sill because water is lost by
boiling condensation evaporation sublimation
(1)
e) A substance which forms a basic oxide and which is not attracted by a magnet could be
carbon copper iron sulphur
(1)
f) Sand is most easily separated from water by
chromatography distillation filtration melting
(1)
2. Methane burns in air to form two products. Name them, give a test which might be used to identify each one and the expected result of each test.
Product 1: (1)
Test: (1)
Result: (1)
Product 2: (1)
Test: (1)
Result: (1)
3. Name two air pollutants and give a different source for each.
Pollutant 1: (1)
Source: (1)
Pollutant 2: (1)
Source: (1)
4. For each of the metals below, give one property which makes it particularly suitable for the use given.
Copper is used to make the bottoms of some saucepans because
(1)
Aluminium is used to make aircraft because
(1)
Gold is used to make jewellery because
(1)
5. A mixture of iron and sulphur was prepared and heated gently. The mixture became red hot and a black solid product was formed.
(a) Complete the word equation
iron + sulphur --->
(b) Explain why the mixture became red hot.
(1)
(c) Explain why the black solid was not attracted to a magnet.
(2)
6. (a) The diagram shows a roaring Bunsen burner flame. Is the air hole open, half-open, or closed?
(1)
(b) On the diagram, mark with a C the coldest part of the flame and mark with an H the hottest part of the flame.
(2)
7. (a) What is meant by the word atom?
(2)
(b) What is meant by the word molecule?
(2)
8. Copper carbonate reacts with dilute sulphuric acid to give a gas.
(a) What is the gas? (1)
(b) What is the chemical name for tne copper-containing compound which is also formed?
(1)
9. Rain-water is slightly acidic and is able to dissolve limestone rock (calcium carbonate), causing weathering.
(a) (i) Name two gases which dissolve in rain-water to make it acidic.
1. (1)
2. (1)
(ii) What process is a major source of both of these gases?
(1)
(b) To what value would you expect the pH of rain-water to be nearest: 1, 5, 7 or 10?
(1)
(c) Limestone can be used to reduce the acidity of soils.
(i) What type of reaction occurs when the acidity in soils is reduced by limestone?
(1)
(ii) Give a word equation for the reaction between hydrochloric acid and limestone (calcium carbonate).
(2)
10. Jeremy. was trying to prepare some copper trom a copper ore, called malachite, which contains copper carbonate. He wrote out the following experimental plan:
Step 1 Grind the ore.
Step 2 Pour on some sulphuric acid and leave to stand for 10 minutes.
Step 3 Filter off any solid which does not dissolve and keep the filtrate.
Step 4 Wash the solid on the filter paper with water and add the washings to the filtrate.
Step 5 Add a suitable metal powder to displace the copper from solution.
(a) (i) Why did Jeremy suggest grinding the ore before treating it with acid?
(1)
(ii) How could he tell that he had added enough sulphuric acid to react with all the copper carbonate in the ore?
(1)
(b) How might he have improved Step 2 of his plan?
(1)
(c) What was the purpose of washing with water in Step 4?
(1)
(d) Name a suitable metal for use in Step 5.
(1)
(e) After Step 5 Jeremy was left with copper mixed with some of the metal he used to displace the copper from solution. Explain how he could obtain pure copper from this mixture.
(3)
(f) Jeremy decided to dry his copper by heating it with a roaring Bunsen burner flame. When he did so, it all turned black. His teacher told him that the copper had been oxidised and that he would have to heat it with a reducing agent to remove the black coating.
(l) Explain why the copper turned black .
(2)
(ii) Name a suitable reducing agent to remove the black coating.
(1)
(iii) Write a word equation for the-reaction between the reducing agent and the black coating.
(2)
11. Susan wanted to find out whether the substances which give tomatoes their red colour are the same as those responsible for the colour of carrots. She decided to use chromatography. She ground up a sample of carrot with some propanone and filtered the mixture to give a clear solution.
(a) Why do you think she used propanone, rather than water?
(1)
(b) Her finished chromatogram is shown in the diagram.
(i) Why do you think Susan drew her starting line with a pencil, rather than with a ball-paint pen?
(1)
(ii) Are the substances in the tomato the same as those in the carrot? Explain your answer.
(2)
(c) Describe how she could carry out the chromatography experiment.
(4)