Core Practical: Investigating Concentration and Rate

This lesson covers the core practical on investigating how concentration affects the rate of reaction, as required by the Edexcel GCSE Combined Science specification (1SC0). You will learn the method for carrying out this investigation, how to collect and analyse data, and how to evaluate the experiment.

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Background Theory

The rate of a chemical reaction is how fast reactants are converted into products. One factor that affects rate is the concentration of a reactant in solution.

Increasing the concentration of a reactant increases the rate of reaction because there are more particles per unit volume, so collisions between reactant particles occur more frequently, leading to more successful collisions per second.

This links to collision theory — for a reaction to occur, particles must collide with sufficient energy (the activation energy).

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The Investigation

Aim

To investigate the effect of changing the concentration of hydrochloric acid on the rate of reaction with marble chips (calcium carbonate).

Reaction

$\text{CaCO}_3(s) + 2\text{HCl}(aq) \rightarrow \text{CaCl}_2(aq) + \text{H}_2\text{O}(l) + \text{CO}_2(g)$CaCO3​(s)+2HCl(aq)→CaCl2​(aq)+H2​O(l)+CO2​(g)

Carbon dioxide gas is produced, so you can follow the reaction by: