N2(g) +O2(g)=2NO(g) Kc=0.10 at 2000 Celsius Starting with initial concentrations of 0.040 mol/L of N2 and 0.040 mol/L of O2, calculate the equilibrium concentration of NO in mol/L.

Question

having trouble with equilibrium do not seem to get the hang of it.

Answer 1

Use an ICE table to help you find the equilibrium values.

N2(g) + O2(g) ====> 2NO(g)

0.04..........0.04..................0.........Initial

-x.............-x.....................+2x.........Change

0.04-x.....0.04-x...............2x..........Equilibrium

Kc = [NO]² / [N₂][O₂] ... now plug in the values from the ICE table

Kc = 0.10 = (2x)² / (0.04-x)(0.04-x)

4x² = 0.1x² - 0.008x + 0.00016

3.9x² + 0.008x - 0.00016 = 0

Solving the quadratic...

x = 0.00546 M

2x = [NO] = 2 x 0.00546 M = 0.0109 M = 0.011 M = [NO]

(please do check the math)