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.