Entropy

Entropy

measure of disorder in system the more the disorder the higher the entropy

How does number of particles affect entropy?

increase in number of particles = increases entropy as energy can be distributed more ways

Explain positive entropy change

system more random/disordered = energy more spread out = +ive

Explain negative entropy change

system less random/disordered = energy conc = -ive entropy

How to calculate entropy change + unit

ΣS˚products — ΣS˚reactants J K^-1 mol^-1

Explain Feasibility + how it is affected?

• whether a reaction is able to happen + is feasible/spontaneous

• affected by temp change + entropy change + enthalpy change

• e.g. if reaction forms gases from solid + number of mol increases its entropically favourable

What are standard conditions for entropy change?

100 kPa 298K 1 mol of substance

What is Free energy change?

overall energy change in chemical reaction

Gibbs Equation for Free energy change

∆G = ∆H - T∆S

∆H → enthalpy change

T → temp

∆S → entropy change

When is a reaction feasible?

when ∆G decreases/negative value (so below or 0)

What are the limitations of Gibbs equation?

• doesn’t take into account the rate of reaction or activation energy

• so equation may say reaction is feasible but acc may not occur/very slow as will have really slow rate of reaction