Measuring the enthalpy of neutralisation
- The standard enthalpy change of neutralisation is the enthalpy change when solutions of an acid and an alkali react together under standard conditions to produce 1 mole of water.
- Enthalpy changes in neutralization reactions are always negative, meaning that heat is always released in the environment during neutralization reactions.
- For reactions involving strong acids and alkalis, the values are always very closely similar, with values between -57 and -58 kJ mol-1.
- The reason for this similarity in value is that the neutralisation reactions are basically reactions between H+ and OH-. The other metal and non-metal ions present in association with these are merely spectator ions having no contribution in the overall enthalpy change.
- So for example:
But what actually happens is,