A student used the apparatus in Figure 13 to investigate the rate of the reaction between a metal and dilute hydrochloric acid - Edexcel - GCSE Chemistry - Question 8 - 2022 - Paper 1

To find the mean rate of production, we first determine the total volume of hydrogen produced in the first 90 seconds from the graph. Suppose the total volume is 45 cm³. Then we calculate:

$\text{Mean Rate} = \frac{\text{Total Volume}}{\text{Total Time}} = \frac{45 \text{ cm}^3}{90 \text{ seconds}} = 0.5 \text{ cm}^3/\text{s}$

The measurements could have been stopped at 9 minutes because the reaction would have reached completion, meaning no further gas is produced, indicating that the reaction has ended.

Increasing the concentration of acid increases the number of acid particles in a given volume. This leads to a higher frequency of collisions between reactant particles, resulting in an increased rate of reaction due to more successful collisions.

D use the same metal but in a powdered form is correct. Using a powdered form increases the surface area, thus allowing for more effective collisions and a faster rate of reaction.

The student can use a hammer to carefully crush the large marble chips into smaller pieces. To ensure uniformity, the student can then sieve the crushed marble to separate the smaller chips from the larger fragments, thereby obtaining both small and medium sized marble chips.