Question

What will be the order of reaction for a chemical change having log $t_{1/2}$ vs log a? (where a = initial concentration of reactant; $t_{1/2}$ = half-life?

• A. Zero order
• B. First order
• C. Second order
• D. None of these

Answer 1

Answer: (A)

Zero order

We know that half life period $\left(t_{1/2}\right)$ of $n-th$ order reaction is given as:-

$t_{1/2}\propto {\left(\frac{1}{\left[A\right]}\right)}^{n-1}$

where $\left[A\right]$= concentration of reactant

Now, if $n=0$ (for zero order reaction)

$t_{1/2}\propto {\left(\frac{1}{\left[A\right]}\right)}^{-1}$

$\Rightarrow t_{1/2}\propto \left[A\right]$

$\Rightarrow t_{1/2}=C\left[A\right]$

where, $C$ is proportionality constant

$\Rightarrow \log t_{1/2}=\log \left[A\right]+logC$

So, this reaction holds good for zero order reaction.