Wednesday, 19 February 2014

Bit of Chemistry- Enthalpy Change Definitions

Enthalpy Change Definitions
Enthalpy of Formation  
The standard molar enthalpy of formation, is the enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions with all reactants and products in their standard states.
The Enthalpy of Atomisation
The standard enthalpy change of atomisation, is the enthalpy change which accompanies the formation of one mole of gaseous atoms from the element in its standard state, with the reaction taking place under standard conditions.
First Ionisation Energy
The first ionisation energy is the standard enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge.
The second ionisation energy refers to the loss of a mole of electrons from a mole of single positively charged ions.
The First Electron Affinity
The fist electron affinity is the standard enthalpy change when one mole of gaseous atoms is converted to a mole of gaseous ions, each with a single negative charge.
 The Second Electron Affinity
The second electron affinity, is the enthalpy change when one mole of electrons is added to a mole of gaseous ions each with a single negative charge to from ions each with two negative charges.
Lattice Formation of Enthalpy
The lattice formation enthalpy, is the standard enthalpy change when one mole of solid ionic compound is formed from its gaseous ions
Enthalpy of Hydration
The enthalpy of hydration, is the standard enthalpy change when water molecules surround one mole of gaseous ions.
Enthalpy of solution
The enthalpy of solution, is the standard enthalpy change when one mole of solute dissolves completely in sufficient solvent to from a solution in which the molecules or ions are far enough apart not to interact
Mean Bond Enthalpy

The enthalpy change when one mole of gaseous molecules each breaks a covalent bond to from two free radicals, averaged over a range of compounds. 

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