Enthalpy Flashcards
Standard enthalpy change of reaction
The enthalpy change when the reaction occurs in the molar quantities shown in the chemical equation under standard conditions
Standard enthalpy change of formation
Enthalpy change when 1 mile of a compound is formed from its constituent elements in their standard states under standard conditions
Standard enthalpy change of combustion
The enthalpy change when 1 mole of a substance is completely burned in oxygen under standard condition
Standard enthalpy change of neutralisation
The enthalpy change when an acid and an alkali react together under standard conditions to form 1 mole of water
Standard conditions
100kPa
298K
Formula for Enthalpy change
Q=mc delta t
OR
Products enthalpy -reactants enthalpy
Standard state
The physical state of a substance under standard conditions
Activation energy
Minimum energy required to start a reaction (by the breaking of bonds)
Enthalpy
The heat content that is stored in a chemical reaction
Exothermic
More energy is released making bonds than is taken in by breaking bonds.
Endothermic
More energy is taken in by breaking bonds than is released by making bonds
Specific heat capacity
The energy required to raise the temperature of 1g of a substance by 1 degree celsius.
Bond enthalpy
The enthalpy change when breaking 1 mole of a given bond in gaseous molecules.
What does each part of Q=mc delta T stand for?
Q = energy transfer (J)
m = mass of what you’re heating (g)
c = specific heat capacity (JK-1mol)
delta T = temperature change (degrees)
How do you work out enthalpy change?
Q/(1000Xn)
