Given Kp, find Kc

Question

Calculate K_c for the following reaction,

2 SO₂(g) + O₂(g) <=> 2 SO₃(g);

K_p = 71.3 at 65 ^o C

Give your answer to the nearest whole number.

please explain your answer

Answer 1

You need to know the relationship between the two equilibrium constants. That relationship is...

Kc = Kp/(RT)^Δn

Kc = ?

Kp = 71.3

R = gas constant = 0.0821 L-atm/K-mol

T = temperature in Kelvin = 65 + 273 = 338K

Δn = change in number of moles of gas = 2 - 3 = -1 (this is obtained by moles product - moles reactant)

Kc = 71.3 /(0.0821 * 338)^-1

Kc = 71.3 / (27.75)^-1

Kc = 1979