Question

2 H2(g) + 2NO(g) → N2(g) + 2H2O(g) is Rate=k[H2][NO]2 (at least at low concentrations of H2). A possible mechanism for this reaction with two steps and an oxygen atom intermediate might take the form: H2 + 2NO → N2 + X + O (Step 1; k1) O + Y → Z (Step 2; k2)

A. Identify the chemical species X, Y, and Z in the mechanism.

Answer 1

Answer : The chemical species X, Y, and Z in the mechanism are $H_2O$, $H_2O$ and $H_2$ respectively.

Explanation :

The given overall balanced reaction is:

$2H_2(g)+2NO(g)\rightarrow N_2(g)+2H_2O(g)$

The two intermediate reactions are:

(1) $H_2+2NO\rightarrow N_2+X+O$

(2) $O+Y\rightarrow Z$

In reaction 1, there are 2 hydrogen atoms present on left side of reaction but there is no hydrogen atom present on right side of the reaction and there are 2 oxygen atoms present on left side of reaction but there is 1 oxygen atom present on right side of the reaction.

So, in order to balance the chemical reaction we are adding water molecule $(H_2O)$ on right side of the reaction. So, the reaction 1 will be:

$H_2+2NO\rightarrow N_2+H_2O+O$

Thus, the chemical specie X will be $H_2O$

Now comparing the reaction 1 and the overall reaction we conclude that there are 2 molecules of $H_2O$ present on right side of the reaction.

So, in order to balance the number of water molecules we are taking the chemical specie Z as $H_2O$ and to complete the reaction one $H_2$ molecule are adding on the left side of the reaction 2. So, the reaction 2 will be:

$O+H_2\rightarrow H_2O$

Thus, the chemical specie Z and Y will be $H_2O$ and $H_2$ respectively.