Question

The following homogeneous gaseous reactions were experimentally found to be second order overall.
1. $ 2NO \rightarrow N_2 +O_2 $
2. $ 3O_2 \rightarrow 2O_3 $
3. $ N_2O_3 \rightarrow NO +NO_2 $
4. $ H_2+I_2 \rightarrow 2HI $

• A. 3 only
• B. 1 and 3
• C. 1 and 4
• D. 3 and 4
• E. 1, 2 and 3

Answer 1

Answer: (C)

$ 2NO\xrightarrow{{}}{{N}_{2}}+{{O}_{2}} $ rate $ =k{{[NO]}^{2}} $
Hence, order of reaction is 2. $ {{H}_{2}}+{{I}_{2}}\xrightarrow[{}]{{}}2HI
$ rate $ =k[{{H}_{2}}][{{I}_{2}}] $
Hence, order of reaction is $ (1+1)=2 $
Therefore, these reaction are most likely to be elementary reaction that occur in one step.