Entropy Source: http://rhschemistry.sfinstructionalresources.wikispaces.net/Ms.Kramer's+Page

Spontaneous Process A physical or chemical change that occurs with no outside intervention

What is an example of a spontaneous reaction? H2O (s)  H2O (g) ΔH = 6.01 kJ

ENTROPY (S) Entropy is a measure of the disorder or randomness of the particles in a system

The LAW OF DISORDER A spontaneous reaction always proceeds so that the entropy of the universe increases

Δssystem= sproducts – sreactants ΔS < 0 : the reaction is not spontaneous ΔS > 0 : the reaction is spontaneous

Predicting entropy Entropy increases with changes in state

Predicting ENTROPY Dissolving a gas in a solvent always decreases entropy

PREDICTING entropy Assuming no other changes in physical state, the entropy of a system increases when the number of molecules increases

Predicting entropy With some exceptions, you can usually predict the change in entropy when a solid or liquid dissolves to form a solution

Predicting entropy An increase in temperature always is accompanied by an increase in entropy

PRACTICE Negative Positive