Chemistry 5070 · O Level · Rate of reaction

Rate of reaction — practice question

A student places large lumps of copper(II) carbonate into dilute hydrochloric acid, and the copper(II) carbonate is in excess.
(a)[1]

Complete the equation by inserting the state symbols for the products. $\text{CuCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CuCl}_2(\ldots) + \text{H}_2\text{O}(\ldots) + \text{CO}_2(\ldots)$

(b(i))[2]

In a different experiment, powdered copper(II) carbonate is used rather than large pieces of copper(II) carbonate. Every other condition and the mass of copper(II) carbonate remain unchanged. Draw a line on the grid in Fig. 5.1 to show how the mass of the reaction mixture changes with time.

(b(ii))[2]

The initial experiment is carried out again using large pieces of copper(II) carbonate and hydrochloric acid at a higher concentration. All other conditions stay the same. Describe and explain the change in rate of reaction when hydrochloric acid of a higher concentration is used.

(c)[3]

Excess copper(II) carbonate is mixed with $22.0\,\text{cm}^3$ of $0.500\,\text{mol dm}^{-3}$ hydrochloric acid. Calculate the volume of carbon dioxide produced at room temperature and pressure. Give your answer to two significant figures.

(d(i))[2]

Describe the observations seen when: • a few drops of aqueous ammonia are added to an aqueous solution containing copper(II) ions • excess aqueous ammonia is added to an aqueous solution containing copper(II) ions.

(d(ii))[1]

A copper ionic compound has the formula $\text{Cu}_2\text{O}$. Deduce the oxidation number of copper in $\text{Cu}_2\text{O}$.

(e)[3]

Describe the method for preparing crystals of ammonium chloride from aqueous ammonia and dilute hydrochloric acid.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: The products are CuCl2(aq), H2O(l) and CO2(g).

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