Chemical Kinetics - Result Question 29
####29. Consider a reaction, $a G+b H \rightarrow$ products. When concentration of both the reactants $G$ and $H$ is doubled, the rate increases by eight times. However, when concentration of $G$ is doubled keeping the concentration of $H$ fixed, the rate is doubled. The overall order of the reaction is
(2007, 3M)
(a) 0
(b) 1
(c) 2
(d) 3
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Answer:
Correct Answer: 29. (a)
Solution:
- Rate $\propto[G]^{m}[H]^{n}$
$\because$ Rate is double on doubling the concentration of $G$ and maintaining $H$ constant, $m=1$, i.e. $R \propto[G]$.
Also, when both concentration of $G$ and $H$ are doubled, rate increases by a factor of 8 . Here rate is increasing by a factor of 2 due to $G$ (first order in $G$ ), therefore, factor due to $H$ is 4 .
$$ \begin{array}{lll} \Rightarrow & R & \propto[H]^{2} \ \Rightarrow & \text { Overall order } & =m+n=1+2=3 \end{array} $$
