An acid will usually release heat when it reacts.
In this reaction we are going to react an acid with an alkali and measure the temperature change during the reaction.
The acid will react to produce a salt and water – no gas is produced. Also, in this reaction there is no colour change. However, the pH will change – you could measure this as described in the previous reaction.
Apparatus and chemicals
|Initial temperature of hydrochloric acid / °C||Highest temperature reached in reaction / °C||Temperature change / °C|
During this reaction the H+ ions from the acid and the OH- ions from the alkali react together to form water. As this happens, energy is released which is detected by the thermometer. The term we use to describe the release of energy is a chemical reaction is exothermic (the ‘exit’ of energy).