Enthalpy Flashcards
What is enthalpy?
The energy content of a substance (taken as a measurement of the heat content).
Exothermic reaction
Reaction in which energy is given out.
Endothermic reaction
Reaction in which energy is taken in.
What is activation energy?
The energy required by colliding molecules to create an activated complex
What is an activated complex?
An unstable arrangement of atoms which can result in the formation of the product or reverse back to the reactants.
Effect of a catalyst:
providing alternative pathways for a reaction which have a lower activation energy.
Catalyst of the same state as the reactants:
homogeneous
Catalyst in a different state of the reactants:
heterogeneous.
catalysts do not
affect the change in enthalpy.
Definition of enthalpy of combustion of a substance
is the enthalpy change when one mole of the substance burns completely in oxygen.
Definition of enthalpy of solution of a substance
is the enthalpy change when one mole of the substance dissolves in water.
Enthalpy of neutralisation of an acid
is the enthalpy change when the acid is neutralised to form one mole of water.
Potential energy diagram can be used to show
the enthalpy change of a reaction.
in terms of energy enthalpy change is
the difference between potential energy levels.
draw the effect of a catalyst in a reaction on a graph
activation energy would be lower the rest is the same
