Gibbs Free Energy, Equilibrium, van’t Hoff Plots

Question 1

Define Gibbs Free Energy

Answer 1

A state variable
G (in J or kJ)
G = H - TS

Question 2

How do you know if a reaction is spontaneous with G?

Answer 2

Used to determine whether a process is spontaneous if done under constant temperature and pressure conditions.

G < 0 Spontaneous
G = 0 Reversible; equilibrium
G > 0 not spontaneous

Question 3

How do you find the change in G of a reaction?

Answer 3

Change in G = { G products - { G reactants

Question 4

What if the relationship between Change in G and Change in G naught?

Answer 4

ChangeinG = Change in G naught + RT InQ

Question 5

How can you tell if a reaction is spontaneous based on the Q and K?

Answer 5

Q < K = spontaneous
Q > K = non-spontaneous
Q = K = reversible; equilibrium

Question 6

What is the van’t Hoff Plot equation?

Answer 6

InK = (-H/RT) + (S/R)

Question 7

How do you get the slope (m) of a plot?

Answer 7

m = -H/R

Question 8

How do you get the y-intercept of a plot?

Answer 8

b = S/R

Question 9

How do you get change in G naught at Equilibrium?

Answer 9

Change in G naught = -nRT lnK