Question

For a reaction $2NO\left(g\right)+C{l}_2\left(g\right)\to 2NOCl\left(g\right)$, when concentration of $C{l}_2$ is doubled the rate of reaction becomes two-times of the original. When the concentration of $NO$ is doubled the rate becomes four times. What is the order of the reaction?

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

The correct option is C $3$

Let the rate law be given by:

Rate $=K\left[NO{]}^x\right[C{l}_2{]}^y,$ order $=x+y$

Given, $2\times rate=K\left[NO{]}^x\right[2C{l}_2{]}^y$

$⟹2=2^y$ or $y=1$

Also, $4\times rate=K\left[2NO{]}^x\right[C{l}_2{]}^y$

$⟹4=2^x$ or $x=2$

$\therefore$ order $=2+1=3$