Qualitative Analysis - Testing for cations, anions and gases (Test 1)

The test is on qualitative analysis, testing for cations, anions and gases. To revise this topic, click here. If you would like to try a short quiz on this topic before attempting the test, click here.

The total score for this test is 10 marks. You should complete the test in 10 minutes.

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Section A: Multiple Choice (5 marks)
1) Which pair of reagents could be used in a test for chloride ions in aqueous solution?
A. aqueous barium nitrate and nitric acid
B. aqueous barium chloride and hydrochloric acid
C. aqueous silver nitrate and nitric acid
D. aqueous silver nitrate and hydrochloric acid

2) One mole of compound X gives two moles of ions in aqueous solution. X reacts with sodium carbonate to give an acidic gas.

Which of the following could X be?

A. calcium hydroxide
B. hydrochloric acid
C. sodium hydroxide
D. sulfuric acid

3) An aqueous solution of compound Y reacts with aqueous sodium hydroxide to form a blue precipitate. This aqueous solution of compound Y also reacts with acidified barium nitrate solution to give a white precipitate. 

What is X?

A. copper(II) chloride
B. copper(II) sulfate
C. iron (II) chloride
D. iron (II) sulfate

4) Which of the following reagent could be used to distinguish aqueous sodium chloride from aqueous sodium nitrate?

A. sulfuric acid 
B. acidified barium nitrate solution
C. acidified silver nitrate solution
D. ammonia solution

5) Compound Z is insoluble in water. When nitric acid is added to Z, Z dissolves, giving out an acidic gas. When aqueous ammonia is added to the resultant solution, a white precipitate is formed. This white precipitate then dissolves in excess aqueous ammonia, giving a colourless solution. 

What is Z?

A. lead(II) carbonate
B. zinc carbonate
C. lead (II) nitrate
D. zinc nitrate

Section B: Open- ended questions (5 marks)
1) Compound A is a white solid, and dissolves in water to give a colourless solution.

When a solution of A is added to aqueous barium nitrate and nitric acid, a white precipitate is

formed.

When a solution of A is added to aqueous sodium hydroxide dropwise until in excess, a white precipitate is formed. This white precipitate is soluble in excess aqueous sodium hydroxide, giving a colourless solution.

When a solution of A is added to aqueous ammonia dropwise until in excess, a white precipitate is formed. This precipitate is insoluble in excess aqueous ammonia.


i) Predict the identity of A. (2 marks)
ii) Write an chemical equation between a solution of compound A and acidified barium nitrate solution. Include state symbols in your answer. (1 mark)
iii) Write an ionic equation for the formation of the white precipitate, when a solution of compound A is added to aqueous sodium hydroxide.



Answers

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Section A:
1) C  
2) B
3) B
4) C
5) B

Section B:
1) i) aluminium sulfate (note: lead(II) sulfate is wrong, as it is insoluble in water)
ii) Al2(SO4)3  (aq) + 3Ba(NO3)2 (aq) ---> 3BaSO4 (s) + 2Al(NO3)3 (aq)
iii) Al3+ + 3OH- ---> Al(OH)3

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