Standard Enthalpy Changes

SEP of reaction

The standard enthalpy change is the energy change when molar quantities of reactants as stated in balanced stoichiometric equation react together at 298K and 1 bar

SEP of formation

The standard enthalpy change of formation is the energy change when one mole of a substance is formed from its constituent elements in their standard states at 298K and 1 bar.

SEP of combustion

The standard enthalpy change of combustion is the energy released when one mole of one mole of a substance is completely burnt in excess oxygen at 298K and 1 bar.

SEP of neutralisation

The standard enthalpy change of neutralisation is the energy released when one mole of water is formed from the reaction of an acid and an alkali at 298K and 1 bar.

SEP of atomisation

The standard enthalpy change of absorbed is the energy absorbed when one mole of gaseous atoms is formed from its element in its standard state at 298K and 1 bar.

Bond Energy

Bond energy is the energy absorbed to break one mole of covalent bonds between two atoms in gaseous molecules to form gaseous atoms.

1st IE

1st IE is the energy absorbed to remove one mole of most loosely held electrons from one mole of gaseous atoms to form one mole of gaseous singly-charged cations.

2nd IE

2nd IE is the energy absorbed to remove one mole of most loosely held electrons from one mole of singly charged cations to form one mole of gaseous doubly-charged cations.

1st EA

1st EA is the energy released when one mole of gaseous atoms gain one mole of electrons to form one mole of gaseous singly-charged anions.

2nd EA

2nd EA is the energy absorbed when one mole of gaseous singly-charged anions gain one mole of electrons to form one mole of gaseous doubly-charged anions.

Lattice Energy

Lattice energy of an ionic compound is the energy released when one mole of ionic solid is formed from its constituent gaseous ions.

SEP of hydration

The standard enthalpy change of hydration is the energy released when one mole of gaseous ions is hydrated to form an infinitely dilute solution at 298K and 1 bar.

SEP of solution

The standard enthalpy change of solution is the energy change when one mole of substance is completely dissolved in a solvent to form an infinitely dilute solution at 298K and 1 bar.