For the reaction, $\mathrm{H}_{2(\mathrm{~g})}+\mathrm{Br}_{2(\mathrm{~g})} \longrightarrow 2…
For the reaction,
$\mathrm{H}_{2(\mathrm{~g})}+\mathrm{Br}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{HBr}_{(\mathrm{g})}, \mathrm{r}=\mathrm{k}\left[\mathrm{H}_2\right]\left[\mathrm{Br}_2\right]^{\frac{1}{2}}$
What is the molecularity and order of reaction respectively?
Monomolecular and $\frac{1}{2}$
Monomolecular and 1
Monomolecular and $\frac{3}{2}$
Bimolecular and $\frac{3}{2}$
Solution
Molecularity $=$ No of reactants $=2$
Order of reaction $=1+\frac{1}{2}=\frac{3}{2}$
Order of a reaction is an experimentally derived quantity and cannot be predicted from balanced equation. We can determine order from an equation only in case of an elementary reaction.