Chemistry 5070 · O Level · Identification of ions and gases

Identification of ions and gases — practice question

A student carries out a sequence of tests with aqueous solution Q and aqueous solution R.
(a(i))[1]

Solution Q is acidic. Solution Q contains one cation and one anion. The tests carried out on Q are shown in Table 3.1. Some observations for these tests are also shown. Describe the expected colour change in test 1.

(a(ii))[1]

A gas is released in test 2. Predict one other observation the student would make in test 2.

(a(iii))[1]

Predict which gas is produced in test 2.

(a(iv))[2]

Describe a test used to confirm this gas’s identity. Include the result of a positive test.

(a(v))[2]

Identify the cation and anion present in Q.

(b(i))[2]

The tests carried out on R are shown in Table 3.2. Some observations for these tests are also shown. Describe how the student carries out a flame test.

(b(ii))[1]

Describe one further observation expected in test 5 using the observations in tests 4 and 5 as a guide.

(b(iii))[3]

Describe one additional test to confirm the identity of the cation in R. Include the result of a positive test.

(b(iv))[1]

Identify the cation present in R.

Worked solution & mark scheme

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