Chemistry 5070 · O Level · Rate of reaction

Rate of reaction — practice question

Calcium carbonate reacts with dilute hydrochloric acid. $\text{CaCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CaCl}_2(aq) + \text{CO}_2(g) + \text{H}_2\text{O}(l)$ Vigorous bubbling is observed. A student studies the rate of this reaction with three calcium carbonate samples, each having a different particle size. For every experiment the student adds all of the calcium carbonate, in excess, to dilute hydrochloric acid in apparatus E. The weighing bottle is put back on the balance. The mass is noted every 30 seconds. In experiment 1 the student uses large lumps of calcium carbonate.
(a)[1]

Name apparatus E.

(b)[1]

Other than mass, which variable is measured in the experiment? Name the apparatus used to measure this variable.

(c)[1]

What causes the mass to decrease?

(d)[2]

Suggest two variables that the student keeps the same so that only the particle size of the calcium carbonate affects the rate of reaction.

(e(i))[1]

Describe how the graphs are used to decide which experiment has the fastest rate.

(e(ii))[1]

Put a number in each box on the graph to identify experiments 1, 2 and 3.

(e(iii))[1]

State how the graph indicates that the reactions have stopped.

(e(iv))[1]

Why do the reactions come to an end?

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