Laws of Thermodynamics and Entropy

Question 1

What does the 1st Law of Thermodynamics say?

Answer 1

Energy can’t be created or destroyed

Question 2

Energy is transferred as what two things?

Answer 2

Heat and work

Question 3

What do we call a process that doesn’t require a continuous supply of energy to proceed once it starts? It may require a spark or nudge to begin.

Answer 3

Spontaneous

Question 4

What do we call a process that requires a continuous supply of energy to proceed?

Answer 4

Non-spontaneous

Question 5

If a forward process is spontaneous, is the reverse process spontaneous or non-spontaneous?

Answer 5

Non-spontaneous

Question 6

ΔE system + ΔE surroundings = ?

Answer 6

ΔE universe or 0

Question 7

What law says that the entropy of the universe increases over time?

Answer 7

2nd Law of Thermodynamics

Question 8

Does a spontaneous process increase or decrease the entropy of the universe?

Answer 8

Increases

Question 9

ΔS system + ΔS surroundings = ?

Answer 9

ΔS universe

Question 10

Which is higher entropy – solid, liquid, or gas?

Answer 10

Gas

Question 11

Which is lower entropy – a substance at a low temperature or the same substance at a high temperature?

Answer 11

Low temperature

Question 12

Which is higher entropy – a gas in a small volume or a gas in a large volume?

Answer 12

Large volume

Question 13

Which has lower entropy – a mixed substance or a separated mixture?

Answer 13

Separated mixture

Question 14

Which has higher entropy – a system with more chemical species or fewer?

Answer 14

More

Question 15

Which has higher entropy – a substance with higher molar mass or lower molar mass?

Answer 15

Higher molar mass

Question 16

In forms of an element (allotropes) that allow atoms more freedom of motion, is entropy higher or lower?

Answer 16

Higher

Question 17

Do compounds with less chemical complexity have higher or lower entropy?

Answer 17

Lower

Question 18

Each quantized energy state of a system is called what?

Answer 18

Microstate

Question 19

What is the Boltzmann equation?

Answer 19

S = k * ln(W)
k = Boltzmann constant, Avogadro’s # divided by gas constant 8.314
W = number of microstates

Question 20

Do more microstates indicate higher or lower entropy?

Answer 20

Higher

Question 21

Does dissolving a non-gas solute increase or decrease entropy?

Answer 21

Increases entropy

Question 22

The entropy of 1 mol of a substance in its standard state is called what?

Answer 22

Standard state (or absolute) entropy S°

Question 23

What is ΔS°, the standard entropy of reaction?

Answer 23

The entropy change when all reactants and products are in their standard states

Question 24

What are the units of S°?

Answer 24

J/mol*K

Question 25

For aA + bB –> cC + dD, what is the formula for ΔS°?

Answer 25

ΔS° = dS°D + cS°C - (bS°B + aS°A)

Question 26

What is the formula for ΔS from temperature and the change in heat?

Answer 26

ΔS = q(rev) / T
rev = reversible

Question 27

Does increasing the temperature of heat flow increase or decrease ΔS?

Answer 27

Decreases ΔS
From ΔS = q/T

Question 28

What does it mean for entropy to be a state function?

Answer 28

It depeds only on the present state and not how it arrived there
ΔS = S(final) - S(initial)

Question 29

What is the formula for ΔS of surroundings

Answer 29

-Q/T
Q = heat flow
T = temperature

Question 30

If ΔS surroundings + ΔS system > 0, is the process spontaneous?

Answer 30

Yes

Question 31

If ΔS surroundings + ΔS system < 0, is the process spontaneous?

Answer 31

No