The graph in Fig. 19.1 shows the volume of oxygen... | Chemistry (9-1) 0971 | Paper 6 Mock 01 | Alternative to Practical

Question 1 Report

The graph in Fig. 19.1 shows the volume of oxygen produced when hydrogen peroxide solution decomposes, with and without a catalyst.

(a) State which curve, P or Q, shows the reaction with the catalyst. [1]
(b) Explain how the graph shows that the catalyst increases the rate of reaction. [2]
(c) Both curves reach the same final volume of gas. Explain why. [2]
(d) Use the graph to find how much longer the reaction without the catalyst takes to produce 30 cm³ of oxygen. [2]

Answer

This question tests how a catalyst affects a reaction, read from a volume-of-oxygen against time graph for the decomposition \( 2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2 \). A catalyst speeds the reaction but does not change how much product forms.

(a) Curve P shows the reaction with the catalyst [1], because it rises far more quickly.

(b) The graph shows the catalyst increases the rate because curve P is steeper and reaches its final volume in a shorter time than curve Q [1], which means the catalysed reaction is faster [1].

(c) Both curves reach the same final volume because the catalyst does not change the amount of product [1]; the same amount of hydrogen peroxide decomposes, so the same volume of oxygen is made [1]. The catalyst provides a lower-energy pathway but is not used up and does not add extra reactant.

(d) Reading across at 30 cm³: curve P reaches 30 cm³ at about 5 s and curve Q at about 24 s [1], so the uncatalysed reaction takes about \( 24 - 5 = 19\ \text{s} \) longer (accept 16 to 22 s) [1].

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Answer Details

(a) Curve P shows the reaction with the catalyst [1], because it rises far more quickly.

Read lesson note on Rates Of Chemical Reaction (JAMB)

Read lesson note on Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Read lesson note on Chemical Kinetics And Equilibrium System (Nigeria Only) (WAEC)

Read lesson note on Rate Of Reaction (OxfordAQA)

Read lesson note on Rate Of Reaction (CIE)

Rates Of Chemical Reaction

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Chemical Kinetics And Equilibrium System (Nigeria Only)

Rate Of Reaction

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The graph in Fig. 19.1 shows the volume of oxygen produced when hydrogen peroxide solution decomposes, with and without a catalyst. (a) State which curve, P...

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The graph in Fig. 19.1 shows the volume of oxygen produced when hydrogen peroxide solution decomposes, with and without a catalyst. (a) State which curve, P...

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