Chemistry 5070 · O Level · Rate of reaction

Rate of reaction — practice question

At room temperature, aqueous hydrogen peroxide breaks down in the presence of a catalyst to make water and oxygen. $2\text{H}_2\text{O}_2(\text{aq}) \rightarrow 2\text{H}_2\text{O}(\ell) + \text{O}_2(\text{g})$.
(a)[2]

Suggest two precautions the student should use to reduce the danger when handling aqueous hydrogen peroxide.

(b)[1]

Give one reason for fitting the cotton wool plug loosely.

(c)[2]

Which two measurements should the student take in order to track the reaction rate in this experiment?

(d(i))[3]

Draw the apparatus used by the student to obtain the results shown in the table. Label the device used to collect and measure the volume of oxygen gas.

(d(ii))[2]

Draw a graph on the grid from the data in the table. Join the points with a smooth curve.

(e(i))[2]

Use the graph to find the volume of oxygen formed in the first $50\,\text{s}$ and in the second $50\,\text{s}$.

(e(ii))[2]

Use your answers to (e)(i) to work out the average volume of oxygen released each second in the first $50\,\text{s}$ and in the second $50\,\text{s}$.

(e(iii))[1]

Use your knowledge of rates of reaction to explain why the two answers to (e)(ii) are different.

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