Chemistry 9701 · AS & A Level · Group 2

Group 2 — practice question

Calcium and its compounds are used in a wide range of applications.
(a(i))[1]

Write an equation for calcium reacting with dilute nitric acid. You do not need to include state symbols.

(a(ii))[2]

If calcium metal is added to dilute sulfuric acid, it reacts strongly at first. After a short while, a layer of calcium sulfate forms on the calcium metal and the reaction stops. Some calcium metal and dilute sulfuric acid are still left unreacted. Explain these observations.

(b(i))[1]

Draw the ‘dot-and-cross’ diagram for the cation found in calcium ethanedioate. Show all of the electrons.

(b(ii))[2]

Draw the displayed formula of the anion found in calcium ethanedioate.

(c(i))[1]

Suggest one use of calcium chlorate(I).

(c(ii))[1]

Chlorate(I) ions are produced when cold aqueous sodium hydroxide reacts with chlorine. Write an ionic equation for this reaction. State symbols are not required.

(c(iii))[1]

The chlorate(I) ion is unstable and breaks down on heating, as shown. Work out the oxidation number of chlorine in each species. Fill in the boxes. $3\text{ClO}^- \rightarrow 2\text{Cl}^- + \text{ClO}_3^-$

(c(iv))[1]

In terms of electron transfer, what happens to the chlorine in reaction (iii)?

(d(i))[1]

Identify the two other products made when lactic acid reacts with calcium carbonate.

(d(ii))[4]

State suitable reagents and conditions for reactions 1 and 3.

(d(iii))[1]

Name the type of reaction that takes place in reaction 2.

(d(iv))[1]

Reaction 4 uses $\text{NaBH}_4$. State the function of $\text{NaBH}_4$ in this reaction.

(d(v))[1]

Lactic acid contains a chiral centre. State what is meant by the term chiral centre.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: $\mathrm{Ca + 2HNO_3 \rightarrow Ca(NO_3)_2 + H_2}$

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