Chemistry 102: acids: Find Kc

Question

10.

Automobiles and trucks pollute the air with NO. At 2000.0°C, K_c for the reaction is 6.22 × 10^–4, and ΔH∘for the reaction is 180.6 kJ.

N2​(g)+O2​(g)2NO(g)

What is the value of K_c at 1000.0°C?

please give exact answer

Answer 1

ln (K2/K1) = -∆H/R (1/T2 - 1/T1)

K1 = 6.22x10^-4

K2 = ?

T1 = 2000C + 273 = 2273K

T2 = 1000C + 273 = 1273K

∆H = 180.6 kJ

R = 8.314 J/Kmol = 0.008314 kJ/Kmol

ln(K2/6.22x10^-4) = -180.6/0.008314 (1/1273 - 1/2273)

ln(K2/6.22x10^-4) = -21,722 (7.86x10^-4 - 4.40x10^-4)

ln(K2/6.22x10^-4) = -21,722 * 3.46x10^-4

ln(K2/6.22x10^-4) = -7.516

(K2/6.22x10^-4) = 5.44x10^-4

K2 = 3.39x10^-7