3.7 Entropy & Feasibility

Question 1

Define entropy

Answer 1

A quantitative measure of the degree of disorder in a system

Question 2

Entropy calculation

Answer 2

sum of products - sum of reactants

Question 3

What does Gibbs free energy tell us?

Answer 3

Whether a reaction is feasible and spontaneous

Question 4

What does it mean if ΔG < 0?

Answer 4

Reaction is feasible

Question 5

What does it mean if ΔG > 0?

Answer 5

Reaction is not feasible

Question 6

ΔG equation

Answer 6

ΔG = ΔH - T ΔS

(always divide ΔS by 1000)

Question 7

Equation to find the temperature at which a reaction is feasible

Answer 7

T = ΔH
——
ΔS

Question 8

What does a -ve ΔH and +ve ΔS mean for ΔG and feasibility?

Answer 8

ΔG always negative
- reaction is always feasible

Question 9

What does a +ve ΔH and -ve ΔS mean for ΔG and feasibility?

Answer 9

ΔG always +ve
- reaction never feasible

Question 10

What does a -ve ΔH and -ve ΔS mean for ΔG and feasibility?

Answer 10

ΔG negative at low temperatures
- reaction feasible at low temperatures

Question 11

What does a -ve ΔH and -ve ΔS mean for ΔG and feasibility?

Answer 11

ΔG negative at high temperatures
- reaction feasible at high temperatures