CHEM 191 Lecture 11

Question 1

what is a spontaneous process

Answer 1

a process that once started will continue without any help - nothing to do with the speed of the reaction

Question 2

what is entropy

Answer 2

a measure of disorder in a system - more disorder means higher entropy

Question 3

if the enthalpy of the universe is increasing how can the entropy of a system decrease during a spontaneous process

Answer 3

the entropy of the surroundings is increasing by a larger amount

Question 4

when is entropy zero

Answer 4

at absolute zero - zero degrees kelvin - -273 celsius

Question 5

which state has the lowest entropy

Answer 5

solids then liquids then gases have the highest

Question 6

how do we calculate the standard entropy of reaction (∆rS)

Answer 6

the sum of entropy of products - the sum of entropy of reactants

Question 7

how can we qualitatively predict a change in entropy

Answer 7

if the reaction results in the formation of a gas from a solid or liquid there will likely be a positive change in entropy - a reaction having fewer moles of products than reactants (all in the same phase) will very likely have a negative change in entropy

Question 8

what is Gibbs energy

Answer 8

the energy available to do work