1.14 Group 7: the halogens
6 exam questions worth 12 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which halogen is a red-brown liquid at room temperature?
Choose one answer.
Correct Not quite: the answer is Bromine
Mark scheme
B
Model answer
B: bromine is a red-brown liquid that gives off an orange vapour.
Describe the test for chlorine gas and give the result.
Mark scheme
- damp (blue) litmus paper (1)
- is bleached / turns white (1)
Model answer
Hold damp blue litmus paper in the gas; chlorine turns it red and then bleaches it white.
Hydrogen reacts with bromine to form hydrogen bromide, HBr.
Write a balanced symbol equation for this reaction and state what forms when hydrogen bromide dissolves in water.
Mark scheme
- H2 + Br2 → 2HBr: formulae (1), balanced (1)
- an acidic solution / hydrobromic acid (1)
Model answer
H2 + Br2 → 2HBr. The hydrogen bromide dissolves in water to form an acidic solution.
Explain why chlorine is more reactive than bromine.
Mark scheme
- chlorine atoms have fewer shells / outer shell closer to the nucleus (1)
- less shielding / stronger attraction for an extra electron (1)
- so chlorine gains an electron more easily (1)
Model answer
A chlorine atom is smaller, so its outer shell is closer to the nucleus with less shielding. The nucleus attracts an extra electron more strongly, so chlorine gains an electron more easily than bromine.
Astatine is below iodine in Group 7.
Predict the state and colour of astatine at room temperature.
Mark scheme
- solid (1)
- dark / black (1)
Model answer
Astatine is a solid at room temperature and is very dark, almost black.
Iron reacts with chlorine to make iron(III) chloride, FeCl3.
Balance the equation: ...Fe + ...Cl2 → ...FeCl3
Mark scheme
- 2Fe + 3Cl2 → 2FeCl3 (1)
Model answer
2Fe + 3Cl2 → 2FeCl3
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