Chemistry 5070 · O Level · Rate of reaction

Rate of reaction — practice question

A learner examines how large pieces of calcium carbonate react with dilute hydrochloric acid at $25\,^{\circ}\text{C}$. Hydrochloric acid is present in excess.
(a)[2]

Fill in the state symbols to complete the equation for this reaction. $\text{CaCO}_3(\ldots\ldots) + 2\text{HCl}(\ldots\ldots) \rightarrow \text{CaCl}_2(\text{aq}) + \text{H}_2\text{O}(\ldots\ldots) + \text{CO}_2(\text{g})$

(b(i))[1]

Deduce the volume of carbon dioxide gas released after 40 seconds.

(b(ii))[2]

The student repeats the experiment with the same mass of smaller pieces of calcium carbonate. All other conditions remain unchanged. Draw a line on the grid in Fig. 3.1 to show how the volume of carbon dioxide changes when smaller pieces of calcium carbonate are used.

(c)[2]

Describe and explain, using collision theory, how the rate of reaction changes when a temperature of $20\,^{\circ}\text{C}$ is used.

(d)[1]

A sample of carbon dioxide is placed in a gas syringe. The end of the gas syringe is then sealed so that no gas can escape. Explain, using kinetic particle theory, why increasing the pressure in the gas syringe decreases the volume of gas when the temperature stays the same.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

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