Enthalpy Changes

The heat content that is stored in a chemical system

A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to surroundings

A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from surroundings

Physical state of a substance under standard conditions of 100kPa and 298K

The enthalpy change that accompanies a reaction in molar quantities expressed in a chemical equation under standard conditions, all products and reactants being in their standard states

Enthalpy change when one mole of a substance reacts completely with O2 under standard conditions, all reactants and products in their standard states

Enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions

Enthalpy change when one mole of water is formed in a neutralisation reaction

Energy required to raise temperature of 1g of a substance by 1C

The average bond enthalpy change when breaking by homolytic fission one mole of a given bond in molecules of a gaseous species

States if a reaction can take place by more than one route, and initial and final conditions are the same, total enthalpy change is the same for each route

Energy released in bond making is greater than energy taken in during bond breaking

Energy released in bond making is less than energy taken in during bond breaking