Enthalpy
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Standard enthalpy of combustion
Enthalpy change when 1 mole of a substance reacts completely in the presence of oxygen, under standard conditions (298K, 1 mol dm3 & 100kPa) whilst all chemicals are in their standard states
Standard enthalpy of neutralisation
Enthalpy change when 1 mole of water is formed in a neutralisation reaction, under standard conditions (100kPa, 298K, 1 mol dm3)
Standard enthalpy of formation
Enthalpy change when 1 mole of a compound is formed from its constituent elements, under standard conditions (298K, 100kPa, 1 mol dm3) whilst all chemicals are in their standard states
Standard enthalpy change of reaction
Enthalpy change when a reaction takes place in the molar quantities shown by the balanced symbol equation under standard conditions (298K, 1 mol dm3, 100kPa)
Enthalpy change equation
Q=mc◇T
Average bond enthalpy
Average enthalpy change when 1 mole of specified bonds are broken
Bond breaking
Endothermic, energy is put in to break bonds
Bond making
Exothermic, energy is released
Apart from heat loss, suggest reasons for different enthalpy of combustion
Different specific heat capacity of water Incomplete combustion
Minimum mass
Mol x mr x %
Explain why a reaction can be exothermic
Less energy is released when bonds are being broken than when bonds are being formed
Why a reaction can be endothermic
Less energy is released when bonds are being formed than when bonds are being broken