Module 3

• Activation Energy, Ea is the minimum energy required to start a reaction by breaking bonds
• Average bond enthalpy is the average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species
• Catalyst: a substance that increases the rate of a chemical reaction without being used up in the process/provides an alternative route for the reaction with lower Ea
• Disproportionation: a redox reaction in which the same element is both oxidised and reduced.
• Dynamic Equilibrium: equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and concentrations do not change
• First ionisation energy: The energy required to remove one electron from one mole of gaseous atoms to form one mole of 1+ ions
• Heterogeneous catalyst: A catalyst that has a different physical state from the reactants
• Homogeneous catalyst: A catalyst that has the same physical state as the reactants
• Periodicity: The repeating trend in properties of the elements across each period of the periodic table
• Enthalpy change of combustion, ∆cH: Complete combustion of 1 mole of a substance
• Enthalpy change of formation ∆fH: Formation of 1 mol of a compound from its elements
• Enthalpy change of neutralisation, ∆neutH: Formation of 1 mol of water from neutralisation
• Enthalpy change of reaction, ∆rH: Enthalpy change associated with a stated equation
• Maxwell Boltzmann Distribution: y-axis= number of molecules, x-axis=energy
• Observation of barium metal + excess of water: a colourless solution with effervescence
• Why is the second ionisation energy greater than the first?

  Proton to electron ration has increased.