The Heat of Reaction is the heat absorbed in a reaction at standard state condition between the numbers of moles of reactants shown in the equation for the reaction.
The Heat of reaction is represented by the symbol ∆H.
The unit of ∆H is kJmol-1.
If the reaction is exothernic, ∆H shows a value of negative. If the reaction is endothernic, ∆H shows a value of positive.
The 4 heat of reaction that you need to know in the syllabus
Heat of Precipitation The heat of precipitation of a substance is the heat change when 1 mole of precipitate formed from its solution of ion under standard state condition.
Heat of Displacement The Heat of Displacement of an element is the heat change when 1 mole of the element was displaced from its compound under standard state condition.
Heat of Neutralisation Heat of neutralisation is the heat change when 1 mol of water is formed by the neutralisation of hydrogen ions by hydroxide ions with measurements made under standard conditions.
Heat of Combustion The Heat of Combustion of a substance is the heat energy evolved when 1 mole of the substance is completely burnt in oxygen.