This question is about sodium halides - AQA - A-Level Chemistry - Question 9 - 2020 - Paper 1
Question 9
This question is about sodium halides.
1. State what is observed when silver nitrate solution is added to sodium fluoride solution.
2. State one observation when s... show full transcript
Worked Solution & Example Answer:This question is about sodium halides - AQA - A-Level Chemistry - Question 9 - 2020 - Paper 1
Step 1
State what is observed when silver nitrate solution is added to sodium fluoride solution.
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Answer
The solution remains colourless, indicating no precipitate formation.
Step 2
State one observation when solid sodium chloride reacts with concentrated sulfuric acid.
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Answer
The reaction produces steamy or white fumes of hydrogen chloride gas.
Step 3
Give an equation for the reaction.
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Answer
The equation for the reaction is:
2NaCl+H2​SO4​→Na2​SO4​+HCl↑
Step 4
State the role of the chloride ions in the reaction.
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Answer
Chloride ions act as a base or proton acceptor during the reaction.
Step 5
Give an equation for the redox reaction between solid sodium bromide and concentrated sulfuric acid.
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Answer
The equation for the redox reaction is:
2NaBr+2H2​SO4​→Na2​SO4​+Br2​+SO2​+2H2​O
Step 6
Explain, using oxidation states, why this is a redox reaction.
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Answer
In the reaction, bromide ions (Br−) change oxidation state from -1 to 0 when forming bromine (Br2​), and sulfur changes oxidation state from +6 (in H2​SO4​) to +4 (in SO2​). Thus, Br is oxidized and H2​SO4​ is reduced, indicating a redox reaction.
Step 7
State what is observed when aqueous chlorine is added to sodium bromide solution.
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Answer
A yellow or orange solution is observed due to the formation of bromine.
Step 8
Give an ionic equation for the reaction.
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Answer
The ionic equation for the reaction is:
Cl2​+2Br−→2Cl−+Br2​
