This question is about the rate of reaction between calcium carbonate and dilute hydrochloric acid - Edexcel - GCSE Chemistry Combined Science - Question 4 - 2021 - Paper 1

To illustrate the apparatus:

1. Draw a conical flask to hold the dilute hydrochloric acid and calcium carbonate.
2. Include a delivery tube connected to the flask that leads to a gas syringe to measure the volume of gas produced. Alternatively, you can draw a delivery tube leading into a water trough below an upturned measuring cylinder.

A water bath set at 45 °C can be used to maintain the temperature of the conical flask during the reaction.

To find the rate of reaction, draw a tangent line at 100 seconds on the graph. Measure the slope of the tangent, which represents the volume of gas produced per second. This can be calculated as: $ext{Rate of reaction} = \frac{\text{Change in volume}}{\text{Change in time}}$

The concentration of the hydrochloric acid should be kept constant during the investigation.

Decreasing the temperature reduces the kinetic energy of the particles involved in the reaction. As a result, the particles move more slowly and collide less frequently with each other. This decrease in collision frequency leads to fewer effective collisions and a lower rate of reaction. Additionally, the likelihood of collisions overcoming the activation energy barrier is reduced, further slowing the reaction.