enthalpy change definitions Flashcards
standard conditions
100kPa, 298K, 1mol/dm3
First ionisation energy
energy change when one mole of electrons is removed from one mole of gaseous ions to form one mole of gaseous 1+ ions. endothermic
first electron affinity
energy change when one mole of gaseous atoms gains 1 mole of electrons to form one mole of gaseous 1- ions. exothermic
second electron affinity
change in energy when one mole of gaseous 1- ions gain one mole of electrons to form one mole of gaseous 2- ions. endothermic
standard enthalpy change of combustion
energy change when one mole of a substance undergoes complete combustion in excess oxygen under standard conditions. exothermic
standard enthalpy change of formation
energy change when one mole of an ionic compound if formed from its elements in their standard states under standard conditions. (usually) exothermic
standard enthalpy change of neutralisation
enthalpy change when an acid and base are neutralised to form one mole of water, under standard contitions. exothermic
enthalpy change of atomisation
energy change when one mole of gaseous atoms are formed from an element in its standard states. endothermic
lattice enthalpy
energy change when one mole of an ionic compound if formed from its gaseous ions under standard conditions. exothermic
enthalpy change of hydration
energy change when one mole of gaseous ions are dissolved in water to form one mole of aqueous ions. exothermic
enthalpy change of solution
energy change when one mole of a compound is completely dissolved in water. can be exo or endothermic
standard enthalpy change of reaction
the enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation with all products and reactants in their standard states under standard conditions
entropy
measure of the degree of disorder of a system.