Answer to Question #209327 in General Chemistry for Mel

Question

Calculate the value of K_p for the equation

C (s) + CO₂ (g) −⇀ 2CO (g) K_p = ?

given that at a certain temperature.

C (s) + 2H₂O (g) −⇀ CO₂ (g) + 2H₂ (g) K_p1 = 3.95

H₂ (g) + CO₂ (g) −⇀ H₂O (g) + CO (g) K_p2 = 0.799

K_p = ?

Answer 1

C(s)+2H2O(g)<->CO2(g)+2H2(g) Kp1=3.33

H2(g)+CO2(g)<->H2O(g)+CO(g) Kp2=.733

Multiply equation 2 by 2 and add to equation 1 to obtain:

C(s) + 2H2O + 2H2 + 2CO2 ==> CO2 + 2H2 + 2H2O + 2CO

Notice 2H2O cancels, 2H2 cancels, 1 CO2 cancels to leave

C(s) + CO2 ==> 2CO

Kp for eqn 1 is Kp1 as listed. Kp for equation 2 multiplied by 2 is K^2p and is K'p2 (0.733)^2. That's because when you multiply and equation by a coefficient(n) the k values is k^n.