The word equation for the reaction between magnesium and dilute hydrochloric acid is magnesium + hydrochloric acid → magnesium chloride + hydrogen The reaction was carried out using the apparatus shown in Figure 11 - Edexcel - GCSE Chemistry - Question 6 - 2019 - Paper 1

There is a loss in mass because hydrogen gas is produced during the reaction between magnesium and dilute hydrochloric acid. As the magnesium reacts, hydrogen escapes from the flask, leading to a reduction in mass.

Initially, there are more magnesium particles exposed to the acid, which leads to frequent collisions between the magnesium and hydrochloric acid particles. As the reaction progresses, the concentration of hydrochloric acid decreases because it is being consumed. This reduction in concentration results in fewer acid particles available to collide with the magnesium, hence the rate of reaction slows.

At a higher temperature, the mass loss after two minutes will be greater. This is because temperature increases the kinetic energy of the particles, leading to more frequent and effective collisions, thus accelerating the reaction.

The line for the magnesium powder experiment would start with a steeper slope compared to the line for magnesium ribbon. This indicates a faster rate of reaction due to the increased surface area of the magnesium powder, which allows for more effective collisions.

A catalyst increases the rate of reaction without undergoing any permanent change itself. It achieves this by providing an alternative pathway with a lower activation energy.

Take a solid catalyst, such as magnesium oxide, and add it to a mixture of reactants in a closed system where gas cannot escape. Measure the initial mass of the catalyst before the reaction. After the reaction has occurred, measure the mass again. The mass of the catalyst should remain unchanged, demonstrating that it is not consumed in the reaction.