Why should the initial temperatures of two reacting solutions be measured before mixing?
To give a starting value for the temperature change
To make sure the solutions are warm enough to react
To calculate the rate of reaction from the temperature
To check that both solutions have the same concentration
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.