Chemistry 5070 · O Level · Identification of ions and gases

Identification of ions and gases — practice question

A student is studying solid Y and solution Z. Solid Y is white and has carbonate ions in it. The student carries out the tests on Y shown in Table 3.1, and some of the observations for those tests are also included.
(a(i))[2]

Predict the identity of the gas formed in test 1. Describe how the student tests the gas to confirm its identity.

(a(ii))[1]

The solution formed in test 1 contains an anion. Name a reagent that reacts with this anion to produce a white precipitate when it is added to the solution formed in test 1 after dilute nitric acid has been added.

(a(iii))[1]

The observations for test 3 are not complete. State one more observation that the student records in test 3.

(a(iv))[2]

Solid Y contains only one cation. From the observations in Table 3.1, the student cannot identify the cation. Use Table 3.1 to name the two cations that could be present in Y.

(a(v))[2]

Describe one extra test that the student carries out on the solution formed in test 1 to identify the cation in Y.

(b(i))[3]

Solution Z contains one cation and one anion. The cation has two non-metals. The student adds aqueous sodium hydroxide to Z in a boiling tube. Describe how the student carries out this test to identify the cation in Z.

(b(ii))[2]

The student adds dilute nitric acid and then aqueous silver nitrate to Z, and a precipitate forms. It is hard to tell whether the precipitate is white or cream. Describe how the student uses separate aqueous solutions of a chloride and a bromide to determine the precipitate colour.

(b(iii))[1]

The student adds dilute nitric acid and then aqueous barium nitrate to Z. Predict the expected observation.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: carbon dioxide gas / CO₂

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI