If more NO NO is added, bringing its concentration to 0.900 M, 0.900 M, what will the final concentration of NO NO be after equilibrium is re‑established?

Question

At equilibrium, the concentrations in this system were found to be  and 

If more  is added, bringing its concentration to  what will the final concentration of  be after equilibrium is re‑established?

Answer 1

Keq = [NO]² / [N₂][O₂] = (0.6)²/(0.2)(0.2) = 9

N₂ + O₂ ===>. 2NO

0.2......0.2..........0.9......Initial

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

0.2+x...0.2+x.....0.9-2x..Equilibrium

K = (0.9-2x)² / (0.2 + x)(0.2 + x) = 9

Use the quadratic equation to solve for x. Then the final concentration of NO at equilibrium will be 0.9 minus that value of x.