1.1 Lattice Enthalpy Flashcards
Define ionic bonds
Strong electrostatic forces of attraction between oppositely charged ions
Define lattice enthalpy
the enthalpy change when one mole of an ionic compound is converted to gaseous ions
Give an equation to express the lattice enthalpy of sodium chloride
NaCl(s) → Na+ (g) + Cl- (g)
Describe the value of lattice enthalpy
- will be endothermic (+ve) as energy is required to break the ionic bonds
- a large value for lattice enthalpy shows there are strong electrostatic forces of attraction between the oppositely charged ions in the lattice.
Define the standard enthalpy change of formation
The energy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.
Give an equation to express the standard enthalpy change of formation of potassium chloride
K(s) + ½ Cl2(g) → KCl(s)
Define standard enthalpy change of atomisation
The enthalpy change when one mole of gaseous atoms is formed from the element in its standard state
Give an equation to express the standard enthalpy change of atomisation of potassium
K(s) → K(g)
Give an equation to express the standard enthalpy change of atomisation of chlorine
½ Cl2(g) → Cl(g)
Define the standard bond dissociation enthalpy
The enthalpy change required to break 1 mol of a covalent bond, everything being in the gas state.
Give an equation to express the standard bond dissociation enthalpy of chlorine
Cl2(g) → 2Cl(g)
Define first ionisation energy
The enthalpy change accompanying the removal of one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
Give an equation to express the first ionisation energy of potassium
K(g) → K+(g) + e-
define second ionisation energy
The enthalpy change accompanying the removal of one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
give an equation to express the second ionisation energy of calcium
Ca+(g) → Ca2+(g) + e-