Physical - 1.8 Thermodynamics Flashcards
Define enthalpy of formation
Enthalpy change when one mole of a substance is formed from its constituent elements with all reactants and products in their standard states and under standard conditions.
Always forms a solid product
e.g. Na2O(s) 2Na(s) + 1/2O2(g) -> Na2O(s)
Define enthalpy of combustion
Enthalpy change when ore mole of a substance undergoes complete combustion in oxygen with all substances in standard states.
e.g. Hydrogen H2(g) + 1/2O2(g) -> H2O(l)
Define enthalpy of neutralisation
Enthalpy change when one mole of water is formed in a reaction between an acid and alkali under standard conditions.
e.g. H2SO4 + NaOH 1/2H2SO4(aq) + NaOH(aq) -> 1/2Na2SO4(aq) + H2O(l)
Define ionisation enthalpy
First ionisation enthalpy is the enthalpy change when each atom in one mole of gaseous atoms loses one election to form one mole of gaseous 1+ ions.
e.g. Magnesium Mg(g) -> Mg+(g) + e-
Second ionisation enthalpy is the enthalpy change when each ion in one mole of gaseous 1+ ions loses one election to form one mole of gaseous 2+ ions.
e.g. Magnesium Mg+(g) -> Mg2+(g) + e-
Define election affinity
First election affinity is the enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1- ions
e.g. Oxygen O(g) + e- -> O-(g)
Second election affinity is the enthalpy change when each ion in one mole of gaseous 1- ions gain one electron to form one mole of gaseous 2 - ions
e.g. Oxygen O-(g) + e- -> O2-(g)
Define enthalpy of atomisation
Enthalpy change when are mole of gaseous atoms is produced from an element in its standard states.
e.g. Iodine 1/2I2(s) -> I(g)
Define hydration enthalpy
Enthalpy change when are mole of gaseous ions become hydrated (dissolved in water) forming one mole of aqueous ions
e.g. Magnesium Ions Mg2+(g) + aq -> Mg2+(aq)
Define enthalpy of solution
The enthalpy change when one mole of a solute dissolves completely in water.
e.g. Magnesium Chloride MgCl2(s) + aq -> Mg2+(aq) + 2Cl-(aq)
Define bond dissociation enthalpy
Enthalpy change when one mole of covalent bonds in broken under standard conditions in the gaseous state
e.g. I-I Bond I2(g) -> 2I(g)
Define lattice enthalpy of formation
Enthalpy change when one mole of a solid ionic compound is formed from its component gaseous ions.
e.g. Magnesium Chloride Mg2+(g) + 2Cl-(g) -> MgCl2(s)
Define lattice enthalpy of dissociation
The enthalpy change when one mole of a solid ionic compound is separated into its component gaseous ions.
e.g. Magnesium Chloride MgCl2(s) -> Mg2+(g) + 2Cl-(g)
Define enthalpy of vaporisation
Enthalpy change when are mole of a liquid is turned into a gas.
e.g. H2O(l) H2O(l) -> H2(g)
Define enthalpy of fusion
Enthalpy change when one mole of a solid is turned into a liquid
e.g. Mg(s) Mg(s) -> Mg(l)
Define enthalpy change
The heat energy change at constant pressure
What is the equation for enthalpy of solution?
Enthalpy of solution = entropy of lattice dissociation + enthalpy of hydration
