Question

Half-life period of a first order reaction is 10 min. Whatpercentage of the reaction will be completed in 100 min

Answer 1

Answer: 99.9 %.

Explanation: To calculate the rate constant, we use the formula:

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

$k=\frac{0.693}{10}$

$k=0.0693 minutes^{-1}$

Rate law expression for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken for decay process

a = initial amount of the reactant

a - x = amount left after decay process

Putting values in above equation, we get:

$100=\frac{2.303}{0.0693}\log\frac{100}{100-x}$

$x=9.9$

Thus the amount decomposed is 9.9 and thus percentage of the reaction completion is 99.9%.

Answer 2

Explanation:

Half-life period of a first order reaction is 10 min. Whatpercentage of the reaction will be completed in 100 min