Question

The half life of the reaction $X \rightarrow Y$ following first order kinetics, when the initial concentration of a is $0.01molL^{- 1}$ and initial rate is $0.00352molL^{- 1}\min^{- 1}{}$ will be

• A. $19.69\min$
• B. $1.969\min$
• C. $7.75\min$
• D. $77.5\min$

Answer 1

Answer: (B)

$1.969\min$

Answer 2

$\frac{dx}{dt} = k\lbrack X\rbrack$ (For a first order reaction)

$0.00352 = k \times 0.01 \Rightarrow k = 0.352$

$t_{1/2} = \frac{0.693}{k} = \frac{0.693}{0.352} = 1.969min.$