22.4 entropy

Question 1

define entropy

Answer 1

a measure of dispersal of energy and the degree of disorder or randomness within a system

Question 2

what are the units of entropy?

Answer 2

JK-1mol-1

Question 3

what are the entropies of solids, liquids and gases?

Answer 3

solids have the smallest entropies
liquids have greater entropies
gases have the greatest entropies

Question 4

if a system changes to become more random…

Answer 4

energy can be spread out more so there will be an entropy change which will be positive

Question 5

if a system changes to become less random…

Answer 5

energy becomes more concentrated so the entropy change will be negative

Question 6

what happens when state changes from solid to liquid to gas?

Answer 6

entropy increases

Question 7

what does melting and boiling do?

Answer 7

increases the randomness of particles
energy is spread out more and entropy is more positive

Question 8

what happens in reactions that produce gas?

Answer 8

an increase in entropy

Question 9

what does production of a gas do ?

Answer 9

increases the disorder of particles so energy is spread other more and entropy is positive

Question 10

what does a change in the number of gas molecules do?

Answer 10

less gas molecules is a decrease in the randomness of particles
energy is spread out less and entropy is negative

Question 11

what is the standard entropy of a substance?

Answer 11

the entropy of one mole of a substance under standard conditions

Question 12

what are standard entropies always?

Answer 12

positive

Question 13

how can standard entropies be used to calculate the entropy change of a reaction?

Answer 13

standard entropy change= sum of standard entropy change of product - sum of standard entropy change of reactants