DEFINITIONS

• WHAT IS AN ENTHALPY CHANGE?

  heat change at a constant pressure
• WHAT ARE STANDARD CONDITIONS?

  100 kPa

  298K / 25 degrees Celsius

  1 moldm^-3
• WHAT IS AN ENTHALPY OF FORMATION?

  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
• WHAT IS AN ENTHALPY OF COMBUSTION?

  enthalpy change when one mole of a substance is burned completely in oxygen
• WHAT IS AN ENTHALPY OF ATOMISATION?

  enthalpy change which accompanies the formation of one mole of gaseous atoms from the elements in their standard states under standard conditions
• WHAT IS FIRST IONISATION ENERGY?

  standard enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge
• WHAT IS SECOND IONISATION ENERGY?

  standard enthalpy change when one mole of gaseous ions each with single positive charges is converted into a mole of gaseous ions each with two positive charges
• WHAT IS FIRST ELECTRON AFFINITY?

  standard enthalpy change when a mole of gaseous atoms is converted to a mole of gaseous ions each with a single negative charge
• WHAT IS SECOND ELECTRON AFFINITY?

  enthalpy change when a mole of electrons is added to a mole of gaseous ions each with a single negative charge to form ions each with two negative charges
• WHAT IS LATTICE ENTHALPY OF FORMATION?

  standard enthalpy change when one mole of solid ionic compound is formed from its gaseous ions
• WHAT IS LATTICE ENTHALPY OF DISSOCIATION?

  standard enthalpy change when one mole of solid ionic compound dissociated into its gaseous ions
• WHAT IS ENTHALPY OF HYDRATION?

  standard enthalpy change when one mole of gaseous ions are converted into aqueous ions/ an aqueous solution
• WHAT IS ENTHALPY OF SOLUTION?

  standard enthalpy change when one mole of solute dissolves in sufficient solvent to form an infinitely dilute solution
• WHAT IS AN INFINITELY DILUTE SOLUTION?

  solution in which molecules/ ions are far enough apart to not interact with each other
• WHAT IS MEAN BOND ENTHALPY?

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