PPT 4

Question 1

What does entropy tell us?

Answer 1

whether a process is spontaneous or not

Question 2

What is a spontaneous process?

Answer 2

a process that occurs without work having to be done to bring it about - it has a natural tendency to occur

Question 3

What is a non spontaneous process?

Answer 3

a process that requires some work to be done to make it happen

Question 4

What are some examples of a spontaneous process?

Answer 4

ice cube melts to water
sitting in a classroom
heat flow between blocks
cards shuffled
partition removed
sucrose dissolves (heat given off to surroundings)
water evaporates (heat flow from dish)

Question 5

What are some examples of a non-spontaneous process?

Answer 5

put ice cube tray in freezer
sitting in the class alphabetically

Question 6

Is disperal of matter spontaneous or nonspontaneous? Why?

Answer 6

yes, isothermal exansion of a perfect gas into vacuum: delta U = 0, spontaneous process is the one that results in disorderly distribution of matter

Question 7

Is disperal of energy spontaneous or nonspontaneous? Why?

Answer 7

yes, hotter region is losing heat while the colder region is gaining heat, spontaneous process is the one that results in orderly distribution of energy

Question 8

What is the driving force of entropy?

Answer 8

disorderliness

Question 9

What is entropy?

Answer 9

a measure of the disorderly dispersal of energy and matter

Question 10

What is the second law of thermodynamics?

Answer 10

the entropy of an isolated system tends to increase (reason why gas molecules disperse)

Question 11

What does reversible mean in terms of entropy?

Answer 11

an infinitesimal change in a variable to change the direction of a process, we looked at mechanical reversibility (reversible expansion of gas) previously, in case of thermal reversibility ther4e is equality of temeprature on either side of a thermally conducting wall, the transfer of heat is smooth without any generation of hot spots

Question 12

What is an example of thermal reversibility?

Answer 12

slightly increasing the temperature makes a substance freeze

Question 13

What is the relationship between the degree of disorder of energy/matter to energy transfer as a result of random motion?

Answer 13

directly proportional

Question 14

What is temperature take into account?

Answer 14

the randomness of motion already present

Question 15

Is there more randomness is a cooler or warmer system? Why?

Answer 15

cooler (lower temperature = less disorder)

Question 16

Give an example of when diorder matters and when it doesnt

Answer 16

matters: talking in a library
does not matter: talking at a rock concert

Question 17

What is a microstate?

Answer 17

the mechanical counting of all possible states of a system

a specific configuration of the locations of atoms/molecules that comprimise a system

Question 18

What can we assume microstates give us?

Answer 18

entropy

Question 19

What is the relationship between number of microstates and entropy?

Answer 19

proportional

Question 20

How can we determine the total number of microstates?

Answer 20

N^n
N = total particles
n = numjber of boxes

Question 21

How can we know which distribution has the highest entropy?

Answer 21

most microstates

Question 22

Why is delta S greater than 0 at az higher volume?

Answer 22

more space for molecules to arrange (more microstates)

Question 23

What is true about the heat in an isolated system?

Answer 23

heat is equal to 0 (and work) since no energy or matter is leaving

Question 24

What is the relationship between temperature and entropy?

Answer 24

proportional

Question 25

When C is constant and Tf is greater than Ti, is entropy +ve or -ve

Answer 25

positive

Question 26

Would we predict a solid, liquid or gas to have a higher entropy state for water? Why?

Answer 26

gas, increase in number of possible states available to the system

Question 27

When is qrev = qp?

Answer 27

during melting/vaporization/phase transition

Question 28

Is delta S an intensive or extensive property?

Answer 28

extensive

Question 29

What is true about a state function?

Answer 29

the sum of each step must be taken into account (added)

Question 30

What is the total entropy of a system when q is reversible? Why?

Answer 30

0, entropy is gained one way and lost the other

Question 31

Why are spontaneous processes irreversible?

Answer 31

they have to take a different path to get back to where they started.

Question 32

Is entropy a state function? Why?

Answer 32

yes, path does not matter