Chemistry 5070 · O Level · Identification of ions and gases

Identification of ions and gases — practice question

A student carries out an investigation on solid Y and solution Z.
(a(i))[1]

Describe how the gas is passed through limewater in test 1. You may use a labelled diagram to support your answer.

(a(ii))[2]

Describe two further observations that the student records in test 1.

(a(iii))[1]

Identify the gas made in test 1.

(a(iv))[1]

Y contains one anion. Use the observations from test 1 to identify this anion.

(a(v))[1]

Use the observations from test 2 to identify the dilute acid used in test 1.

(a(vi))[1]

Identify the cation in Y using the observations from tests 3 and 4.

(b(i))[1]

Solution Z is colourless. The student thinks that Z contains $\text{Cu}^{2+}$ ions. State why the student is incorrect.

(b(ii))[3]

Solution Z contains $\text{K}^+$ ions. Describe how to carry out a flame test on solution Z to confirm the identity of this cation.

(b(iii))[3]

Solution Z contains ions of a Group VII element. Describe a test and the possible results used to identify which Group VII ion is present in Z.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Gas is bubbled through limewater with a pipette or delivery tube

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