Nitrogen and oxygen react together to form nitric oxide, which decomposes to give back the reactants In a container - Chemistry - Chemical and Ionic Equilibrium

Question

Nitrogen and oxygen react together to form nitric oxide, which
decomposes to give back the reactants In a container of one litre
capacity, two moles of nitrogen, two moles of oxygen and four moles
of niric oxide were injected What will be the concentration of
nitric oxide at equilibrium at 1,727o C? The equilibrium
constant for the reaction, at 1,727o C, is 4 1:
(A) 6 01 mol/L
(B) 3 54 mol/L
(C) 4 71 mol/L
(D) 5 84 mol/L

Vartika Jain · Accepted Answer

Dear Student,

N2 + O2 ↔  2NO 2        2             4                
initially2-x   2-x      4+2x        
at equilibrium Kc=4
1We know that, Kc =[NO]2[O2][N2]     =(4+2x1)(2-x1)(2-x1)                       (since concentration=MolesVolume)or, 4
1=(4+2x)(2-x)(2-x)since x<<2Therefore, 2-x≈2So, 4
1(2-x)2=4+2x4 1(4+x2-4x)=4+2x16 4+4 1x2-16 4x=4+2xor, 4 1x2-18
4x+12 4=0or, x2-4 48x+3 02=0or, x=-(-4 48)±(4
48)2-4(1)(3 02)2(1)       =4
48±20 07-12 082       =4
48±2 832       =3
65 or 0 79x≠ 3
65 as x cannot be greater than 2   (this will make [N2] and [O2] at equilibrium negative)x=0
79[NO]=4+2×0
79        =5
58 mol/LHence,correct answer is (D)