4. entropy + Gibbs free energy

entropy

the measure of the number of ways that particles can be arranged and the number of ways that the energy can be shared out between the particles

dissolution

dissolving a solid also increases its entropy as dissolved particles can move freely as they are no longer held in place

more particles means more entropy

the more particles there are the more ways they and their energy can be arranged

calculating entropy change

products - reactants

free energy change

is a measure used to predict whether a reaction is feasible

a reaction is feasible when

ΔG is negative or equal to 0

negative ΔG doesn’t guarantee a reaction will occur or tell you about its rate

the reaction may only be theoretically feasible,

with an extremely high activation energy

or have such a slow rate you wouldn’t be able to notice tis happening at all

exothermic reactions and POSITIVE ENTROPY change

these reactions are feasible at any temperature

endothermic reactions and has a NEGATIVE ENTROPY change

these reactions are not feasible at any temperature

if the reaction is endothermic and entropy is positive

the reaction will only be feasible above a certain temperature

if the reaction is exothermic and enthropy is is positive

reaction is only feasible below a certain temperature

when ΔG is 0

a reaction is JUST feasible

variation in ionisation energy, FROM STRONGEST TO WEAKEST

O²⁺>O> O^- >O^2-

CATION>NEUTRAL ELEMENT>ANION