Calculate the half-life of the first order ...

NCERT Class XII Chemistry
Chapter - Chemical Kinetics
Questions with Solutions

Question : 13 of 39

Marks: +1, -0

Calculate the half-life of the first order reaction from their rate constants given below :

(i) 200 s

^{-1}

(ii) 2 min

^{-1}

(iii) 4 year

^{-1}

Solution:

Half-life period of a first order reaction is given by

t_{1/2} = \frac{0.693}{k} ,

hence

(i)

\;\; t_{1/2} = \frac{0.693}{200}

=3.46 \times 10^{-3} \ \mathrm{s}

(ii)

t_{1/2} = \frac{0.693}{2}

=0.346 \ \mathrm{min}

(iii)

t_{1/2} = \frac{0.693}{4}

=0.173

year

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