A student used the apparatus in Figure 3 to investigate the rate of the reaction between a metal and dilute hydrochloric acid - Edexcel - GCSE Chemistry - Question 2 - 2022 - Paper 1

To determine the rate at which hydrogen gas was produced during the reaction, we first find the volume of hydrogen collected at a specific time and then divide it by that time.

Using the data extracted from the graph, the total volume of hydrogen after 9 minutes is approximately 65 cm³. Therefore, the rate can be calculated as:

$ext{Rate} = \frac{\text{Volume}}{\text{Time}} = \frac{65 \text{ cm}^3}{9 \text{ min}} \approx 7.22 \text{ cm}^3 \text{/ min}.$

The graph indicates that the volume of hydrogen produced increases over time, but the rate of production decreases as the reaction progresses. This occurs because as the reactants are consumed, the collisions between the reactant particles become less frequent, leading to a slower reaction rate.