Using the following equilibria and Kc values:

Question

Using the following equilibria and K_c values:

SO₃(g) + NO(g) ⇆ SO₂(g) + NO₂(g)                  K_c = 5.0 × 10⁸

2 SO₃(g) + N₂(g) ⇆ 2 SO₂(g) + 2 NO(g)           K_c = 1.5 × 10^-4

the calculated value of K_c for the reaction

2 NO₂(g) + N₂(g) ⇆ 4 NO(g) is

Answer 1

This is a problem involving Hess' law

TARGET EQUATION: 2NO₂(g) + N₂(g) ⇆ 4 NO(g)

GIVEN:

(1). SO₃(g) + NO(g) ⇆ SO₂(g) + NO₂(g)                  K_c = 5.0 × 10⁸

(2). 2 SO₃(g) + N₂(g) ⇆ 2 SO₂(g) + 2 NO(g)           K_c = 1.5 × 10^-4

PROCEDURE:

reverse (1) and x 2: 2SO₂ + 2NO₂ <==> 2SO₃ + 2NO ... Kc = 1/(5x10⁸)² = 4.0x10^-18

copy (2) 2SO₃(g) + N₂(g) <==> 2 SO₂(g) + 2 NO(g)  ... Kc = 1.5x10^-4

Add the two together to obtain....

2SO₂ + 2NO₂ + 2SO₃(g) + N₂(g) < ==> 2SO₃ + 2NO + 2 SO₂(g) + 2 NO(g) and simplify to get ...

2SO₂ + N₂ <==> 4NO TARGET EQUATION

K = 4.0x10^-18 * 1.5x10^-4 = 6.0x10^-22