Question

The time for half life period of a certain reaction A $\longrightarrow$ Products is 1 hour. When the initial concentration of the reactant ‘A’, is 2.0 mol L–1, how much time does it take for its concentration to come from 0.50 to 0.25 mol L–1. If it is a zero order reaction?

• A. 4 h
• B. 0.5 h
• C. 0.25 h
• D. 1 h

Answer 1

Answer: (C)

0.25 h

Answer 2

A$\longrightarrow$ product

For zero order reaction

$t_{1/2} \propto \frac{1}{a^{n - 1}}$ a = initial concentration of reactant

t1/2 a

$\frac{\left( t_{1/2} \right)_{1}}{\left( t_{1/2} \right)_{2}} = \frac{a_{1}}{a_{2}};\frac{1}{\left( t_{1/2} \right)_{2}} = \frac{2}{0.50}$

$t_{1/2} = \frac{0.5}{2} = 0.25h.$