Question

For the reaction $2N_2{O}_5\to 4N{O}_2+O_2$ rate at a particular time and rate constant are $1.02\times {10}^{-4}M{s}^{-1}$ and $3.4\times {10}^{-5}M{s}^{-1}$ respectively. Then the concentration of $N_2{O}_5$ at that time will be:

• A. $1.732$
• B. $3$
• C. $1.02\times {10}^4$
• D. $3.4\times {10}^5$

Answer 1

The correct option is B $3$

Unit of rate = $M{s}^{-1}$

Let the rate be of the form

$r=K{\left[N_2{O}_5\right]}^x$

Given unit of rate constant = $S^{-1}$

For dimensional consistenty x=1

and hence, the given reaction is a first order reaction.

$\Rightarrow$ rate $=K\left[N_2{O}_5\right]$

$\Rightarrow 1.02\times {10}^{-4}=\left[N_2{O}_5\right]3.4\times {10}^{-5}$

$\Rightarrow \left[N_2{O}_5\right]=3$