Figure 1 shows the apparatus used to compare the temperature changes during the neutralisation reactions between different dilute acids and an alkali.
In each experiment, 25 cm3 of a different acid of concentration 1.0 mol dm-3 is added to 25 cm3 of 1.0 mol dm-3 sodium hydroxide solution.
State one variable, apart from the concentrations of the solutions used, that must be kept constant in this investigation to ensure a fair comparison.
