Chemistry 5070 · O Level · Identification of ions and gases

Identification of ions and gases — practice question

A student examines solution P and solution Q.
(a(i))[3]

Describe how to carry out a flame test on solution P to confirm this cation.

(a(ii))[6]

Solution P contains an anion made of nitrogen and oxygen. Describe a test to identify the anion in solution P. Include test, observations and identity of anion.

(b(i))[1]

Identify the cation in solution Q from the observations in tests 1 and 2.

(b(ii))[1]

Describe what further action is needed in test 3 so that the white precipitate observed gives a valid conclusion about the anion in solution Q.

(b(iii))[1]

When test 3 is done correctly, the observation remains unchanged. Identify an anion in solution Q.

(b(iv))[1]

The ion identified in (iii) is the only anion present in solution Q. Describe the observation expected in test 4.

(b(v))[1]

Solution Q is acidic. Describe the observation that occurs when sodium carbonate is added to solution Q.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: M1 place wire / splint into solution / P

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