Question

For $n$th order reaction $\frac{t_{1/2}}{t_{3/4}}$ depends on $(n\ne 1)$:

• A. initial concentration only
• B. '$n$' only
• C. initial concentration and '$n$' both
• D. sometimes '$n$' and sometimes initial concentration

Answer 1

The correct option is B '$n$' only

$\frac{1}{a^{n-1}}=\frac{1}{{a_o}^{n-1}}+(n-1)kt$

So,

$t_{1/2}=\frac{2^{n-1}-1}{a_o(n-1)k}$

$t_{3/4}=\frac{2^{2n-2}-1}{a_o(n-1)k}$

$\frac{t_{1/2}}{t_{3/4}}=\frac{2^{n-1}-1}{2^{2n-2}-1}$

So it is depend on ${}^{\prime }{n}^{\prime }$ only.