Gibbs energy and chemical equilibria

Question 1

What is chemical equilibrium?

Answer 1

The concentrations of the products and reactants are constant

Question 2

What is Gibbs energy like at the start of the reaction?

Answer 2

It is high and decreases as the products are formed

Question 3

What is the equation for activity?

Answer 3

{A} = γ [A] / c°
γ = 1 (assumed)
C° = standard concentration 1 mol kg-1

Question 4

What is the equilibrium constant?

Answer 4

K = {C}ᶜ{D}ᵈ / {A}ᵃ{B}ᵇ

Question 5

What is {A}?

Answer 5

Activity of A

Question 6

What equation is used of Gibbs energy to relate to the equilibrium constant?

Answer 6

ΔG° = -RT ln K

Question 7

What is the value of ΔG at equilibrium?

Answer 7

0

Question 8

What equation links the rates of reactants and products when they have attained their values at equilibrium?
A + B C

Answer 8

kf[A][B] = kb[C]

Question 9

What units does K have?

Answer 9

dimensionless

Question 10

What is p°?

Answer 10

Standard pressure

1 bar

Question 11

What equilibrium equation is used for gases and includes pressures?

Answer 11

K = (pc / p°)ᶜ (pd / p°)ᵈ / (pa / p°)ᵃ (pb /p °)ᵇ

Question 12

What is the acid dissociation equation?

Answer 12

Ka = {H+}{A-} / {HA}

Question 13

What is the van’t Hoff equation?

Answer 13

(dlnL / d1/T)pn = - ΔH° / R

Question 14

If ΔH° doesn’t change with temperature, how can you rewrite the van’t Hoff equation?

Answer 14

lnK2 = lnK1 - ΔH° / R (1/T2 - 1/T2)

Question 15

What is the slope of the graph equal to?

Answer 15

Slope = - ΔH° / R