Question

Diazonium salt decomposes as $C_6{H}_5{N}_2^{+}C{l}^{-}\to C_6{H}_{5}Cl+N_2$. At $0^{o}C$, the evolution of nitrogen becomes two times faster when the initial concentration of the salt is doubled, therefore it is:

• A. a first order reaction
• B. a second order reaction
• C. independent of the initial concentration of the salt
• D. a zero order reaction

Answer 1

The correct option is A a first order reaction

The rate of the evolution of nitrogen is equal to the rate of the reaction.

When the initial concentration of the salt is doubled, the rate of the evolution of nitrogen and the rate of the reaction is doubled.

$r=k[A{]}^m$......(1)

$r^{\prime }=2r=k[2A{]}^m$......(2)

From equations (1) and (2), $m=1$

Hence, the reaction is first order with respect to the concentration of the salt.