Q.

Consider the following reaction in a sealed vessel at equilibrium with concentrations of 

N2=3.0×10-3M, O2=4.2×10-3M and NO=2.8×10-3M.

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

If 0.1 mol L-1 of NO(g) is taken in a closed vessel,

what will be the degree of dissociation (α) of NO(g) at equilibrium                 [2024]

1 0.00889  
2 0.0889  
3 0.8889  
4 0.717  

Ans.

(4)

2NO(g)N2(g)+O2(g)0.1000.1-xx2x2

Kc=x2×x2(0.1-x)2

Again, Kc=[N2][O2][NO]2=3×10-3×4.2×10-3(2.8×10-3)2=1.607

x24(0.1-x)2=1.607  x2(0.1-x)=1.607

x0.2-2x=1.26  x=0.252-2.52x

3.52x=0.252  x=0.2523.52=0.0716

Degree of dissociation, α=0.07160.1=0.716