Energetics 2 Flashcards
Standard enthalpy of atomisation of an element
Amount of energy required to produce 1 mole of gaseous atoms from an element in its standard state under standard conditions
Standard enthalpy of atomisations are always…
Endothermic because energy is required to break intermolecular forces/ bonds to form gaseous atoms
Standard enthalpy of atomisation symbol
ΔatH ⦵
First electron affinity
The enthalpy change when 1 mole of electrons is added to 1 mole of atoms in the gaseous state to form 1 mole of gaseous 1- ions
Second electron affinity
Enthalpy change when 1 mole of electrons is added to 1 mole of gaseous 1- ions to form 1 mole of 2- ions
Electron affinity symbol
ΔEaH
Are electron affinities measured in standard states?
No under gaseous state
Lattice enthalpy of formation
The enthalpy change when 1 mole of an ionic compound is formed from its constituent gaseous ions
Lattice enthalpy of formation is always…
Exothermic so negative value because energy is released when ionic compound is formed
Lattice enthalpy of formation symbol
ΔLe form H
Is lattice enthalpy of formation under standard states?
No the ions are in gaseous states
Lattice enthalpy of dissociation
Enthalpy change when 1 mole of an ionic compound is split into its constituent gaseous ions
Lattice enthalpy es of dissociation are always…
Endothermic so a positive value because energy is required to be put in to break the ionic bonds
Enthalpy of hydration
Enthalpy when 1 mole of gaseous ions dissolves in water to form 1 mole of aqueous ions
Enthalpy es of hydration are always…
Negative because gaseous ions dissolve to form new bonds to water molecules thus making bonds is exothermic
