Activity 7.3 – Chemistry Form 4 Chapter 7 (Rate of Reaction)

Activity 7.3:
Solving numerical problems related to rate of reactions

In the presence of manganese(IV) oxide, MnO₂, hydrogen peroxide, H₂O₂ decomposes to water and oxygen. The oxygen gas released is collected in a gas syringe and the volume recorded at intervals of 0.5 minute. The data collected is shown in Table 7.3.



1. Based on Table 7.3, plot a graph of volume of gas against time.

2. Calculate the following average rate of reaction:
(a) For the first minute
(b) For the fifth minute
(c) For the whole reaction

3. Calculate the rate of reaction at the following time:
(a) 1.5 minute
(b) 4.0 minute


Answer:
1.


2.
(a) $$\frac{(22-0) \mathrm{cm}^3}{(1-0) \mathrm{min}}=22 \mathrm{~cm}^3 \mathrm{~min}^{-1}$$
(b) $$\frac{(48-45) \mathrm{cm}^3}{(5-4) \mathrm{min}}=3 \mathrm{~cm}^3 \mathrm{~min}^{-1}$$
(c) $$\frac{50 \mathrm{~cm}^3}{6 \mathrm{~min}}=8.33 \mathrm{~cm}^3 \mathrm{~min}^{-1}$$


3.
(a) 10.62 cm³ min^–1
(b) 4.17 cm³ min^–1