Amount of heat taken in or given out at a constant pressure during any physical or chemical change. Enthalpy change = Sum of bonds broken - Sum of bonds formed
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Enthalpy of Formation
Enthalpy change under standard conditions when I mole of a compound is formed from its elements with all reactants and products in their standard states
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Enthalpy of Ionisation
Standard molar enthalpy change for the removal of an electron from a species in the gas phase to form a positive ion and an electron, both also in the gas phase. Always endothermic.
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Enthalpy of Atomisation
Standard enthalpy change that accompanies the formation of one mole of a gaseous atoms from the element in its standard state. Always endothermic.
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Enthalpy of Dissociation
Standard molar enthalpy change that accompanies the breaking of a covalent bond in a gaseous molecule to form two gaseous free radicals. Always endothermic.
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Free Radicals
Species that result form the homolytic fission of a covalent bond. It contains an unpaired electron.
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Enthalpy of Electron Affinity
Standard enthalpy change when an electron is added to an isolated atom in the gas phase. Exothermic, 2nd Endothermic.
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Enthalpy of Lattice Dissociation
Standard enthalpy change that accompanies the separation of one mole of a solid ionic lattice into its gaseous ions. Always Endothermic.
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Enthalpy of Lattice Formation
Standard enthalpy change that accompanies the formation of one mole of a solid ionic lattice from its gaseous ions. Always exothermic.
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Enthalpy of Hydration
Standard enthalpy change when one mole of gaseous ions is changed to one mole of aqueous ions. Always exothermic.
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Enthalpy of Solution
Standard enthalpy change when one mole of an ionic solid dissolves in enough water to ensure that the dissolved ions are well separated and do not interact with one another.
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Hess's Law
The enthalpy change of a reaction is independent of the route taken
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Born Haber Cycle
Enthalpy of Formation, Enthalpy of atomisation/dissociation, Enthalpy of ionisation, Enthalpy of electron affinity, Lattice formation
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Perfect Ionic Model
Assumption that lattice dissociation enthalpy of an ionic crystal depends solely on the total separation of ions that experience only electrostatic forces. Experimental values higher because ionic compounds posses a degree of covalent bonding
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Mean Bond Enthalpy
Average of several values of the bond dissociation enthalpy for a given type of bond, taken from a range of compounds.
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Spontaneous Change
One that has a natural tendency to occur, without being driven by any external influences.
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Entropy Factor
Increase in entropy is an increase in disorder, heating leads to an increase in disorder. At 0 Kelvin their is perfect order.
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Card 2
Front
Enthalpy of Formation
Back
Enthalpy change under standard conditions when I mole of a compound is formed from its elements with all reactants and products in their standard states
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