In: Chemistry
a mixture of 0.2 mol of NO, 0.1 mol of H2 and 0.2 mol of H2O is placed in 2.0 L at 300 K. At equal [NO] = 0.062. Calculate K
Answer – We are given, moles NO = 0.20 moles , moles of H2 = 0.10 moles
Moles of H2O = 0.2 moles , volume = 2.0 L
Reaction
2 NO(g) + 2 H2(g) -----> N2 (g) +2 H2O(g)
[NO] = 0.20 moles / 2.0 L =0.10 M
[H2] = 0.1 moles / 2.0 L = 0.05 M
[H2O] = 0.20 moles / 2.0 L = 0.10 M
At equilibrium, [NO] = 0.062 M
We need to put Ice chart
2 NO(g) + 2 H2(g) -----> N2 (g) +2 H2O(g)
I 0.1 0.05 0 0.10
C -2x -2x +x +2x
E 0.062 0.05-2x +x 0.10+2x
We know,
At equilibrium, [NO] = 0.062 M = 0.10-2x
So, 2x = 0.10-0.062
= 0.038
So, x = 0.019
So at equilibrium, [H2] = 0.05-2x
= 0.05-2*0.019
= 0.012 M
[N2] = x = 0.019 M
[H2O] = 0.1+2x
= 0.1+0.038
= 0.138 M
So, K = [N2 (g)] [H2O(g)]2 / [NO(g)]2 [H2(g)]2
= (0.019) (0.138)2 / (0.062M)2(0.012)2
= 654