thermodynamics (physical) Flashcards
What does Hess’s law state?
the enthalpy change for a reaction s independent of the route taken
Define standard enthalpy of formation?
the enthalpy change when 1 mole of compound is formed from its constituent elements in standard conditions with all products and reactants in their standard states
what is the standard enthalpy of an element
zero
define enthalpy change of combustion
when one mole of a substance is completely burnt in (excess) oxygen
define enthalpy change of atomisation
enthalpy change when 1 mole of gaseous atoms is formed from a compound in its standard state in standard conditions
define first ionisation energy
energy when one mole of electrons is removed from one mole of gaseous atoms to form 1 mole of gaseous 1+ ions
define 2nd ionisation energy
enthalpy change when one mole of electrons is removed from 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions
define first electron affinity
enthalpy change when 1 mole of gaseous atoms gains 1 mole of electrons to form one mole of gaseous 1- ions
define second electron affinity
enthalpy change when 1 mole of gaseous 1- ions gains one mole of electrons to form 1 mole of gaseous 2- ions
define lattice enthalpy of dissociation
enthalpy change when 1 mole of solid ionic lattice is dissociated (broken into) its gaseous ions
define enthalpy of hydration
enthalpy change when 1 mole of gaseous ions become hydrated/dissolved in water to infinite dilution (water molecules totally surround the ion)
define enthalpy of solution
enthalpy change when 1 mole of solute dissolves completely in a solvent to infinite dilutiom
define mean bond dissociation enthalpy
enthalpy change when 1 mole of covalent bonds is broken with all species in the gaseous state
what is the born haber cycle
thermochemical cycle showing all the enthalpy changes involved in the formation f an ionic compound. starts with elements n their standard states
what factors effect the lattice enthalpy of an ionic compound
size of the ions, charge on the ions