Question

20. The reaction of nitric oxide (NO(g)) with a molecular hydrogen (H2(g)) results in the production of molecular nitrogen and water as follows: 2NO(g) + 2H2(g) N20(g)+2H2O(g) According to the following proposed mechanism of this reaction 2NO(g) k-1 (fast equilibrium) N2O2(g) H2(g)+ N2O2(g) N2O(g)+2H20(g) Which of the following is TRUE A) The reaction rate of hydrogen decomposition is consistent with the observed 3rd order. The reaction rate of hydrogen decomposition is consistent with the observed 4th order. B) C) The reaction rate of hydrogen decomposition is consistent with the observed 2nd order. The reaction rate of hydrogen decomposition is consistent with the observed 1st order. D) The reaction rate of hydrogen decomposition is consistent with the observed zero order. E)

Answer 1

As we know slow step is rate determining step so

Rate = k[H2][N2O2] ----------(1)

From fast equilibrium,

Keq = [N2O2]/[[NO]²

[N2O2] = Keq[NO]² ---------(2)

From equation (1) and (2)

Rate = kKeq. [H2][NO]²

Rate = k'[H2][NO]²

From rate law, reaction rate is observed 3rd order.

(A) is correct