Entropy 5.2.2

Question 1

What is Entropy?

Answer 1

Entropy is a measure of the disorder within a system.

It is based off of the number of ways the energy can be rearranged within a system.

Question 2

Rank the states of matter in decreasing Entropy.

Answer 2

Gas
Aqueous (not a state of matter but it fits here)
Liquid
Solid

Question 3

What are the units and symbol of Entropy?

Answer 3

Units: J K^-1 mol^-1 (Joules per Kelvin per Mole)
Symbol: S

Question 4

What does a superscript θ mean?

Answer 4

It is at standard conditions.

298K and 1atm (100kpa)

Question 5

Do simple substances have high or low Entropy?

Answer 5

Low Entropy

Question 6

Chemical reactions are favoured if they what?

Answer 6

Increase in entropy

Decrease in enthalpy

Question 7

Can endothermic reactions occur spontaneously?

Answer 7

Yes

So long as there is an increase in Entropy

Question 8

What if an exothermic reaction has a decrease in Entropy?

Answer 8

The reaction won’t be spontaneous

Question 9

How is Entropy calculated?

Answer 9

Σproducts - Σreactants

Question 10

What is the equation for Gibb’s Free Energy?

Answer 10

ΔG = ΔH - TΔS

Change in Free Energy = Change in Enthalpy - (Temperature x Change in Entropy)

Question 11

What is ΔG?

Answer 11

Free Energy

Question 12

What happens if ΔG = +ve ?

Answer 12

The reaction will not proceed

Even if ΔH = -ve

Question 13

What happens if ΔG = -ve ?

Answer 13

The reaction will proceed

Even if ΔH = -ve, but it may be slow if it has a high activation energy

Question 14

What is Critical Temperature?

Answer 14

It is the temperature at which a reaction becomes feasible

Question 15

If ΔH = -ve and ΔS = +ve?

Answer 15

The reaction is feasible at all temperatures.

As ΔG will always be negative

Question 16

At the Critical Temperature, what does ΔG=?

Answer 16

ΔG = 0

Question 17

If ΔH = +ve and ΔS = -ve?

Answer 17

The reaction is not feasible at all temperatures.

As ΔG will always be positive

Question 18

If ΔH = +ve and ΔS = +ve?

Answer 18

The reaction will only be feasible over the critical temperature

Question 19

If ΔH = -ve and ΔS = -ve?

Answer 19

The reaction will only be feasible below the critical temperature

Question 20

What is a Spontaneous Reaction?

Answer 20

A reaction that can proceed on its own

Question 21

What does a Spontaneous Reaction cause?

Answer 21

Lower entropy

increased stability