Question

The rate constant for a first order reaction is $7.0\times {10}^{-4}{s}^{-1}$. If initial concentration of reactant is $0.080$ $M$, what is the half life of reaction?

• A. $990s$
• B. $79.2s$
• C. $12375s$
• D. $10.10\times {10}^{-4}s$

Answer 1

Answer: (A)

$990s$

The rate constant for a first order reaction is $k=7.0\times {10}^{-4}{s}^{-1}$

The half life period $t_{1/2}=\frac{0.693}{k}$

The half life period $t_{1/2}=\frac{0.693}{7.0\times {10}^{-4}{s}^{-1}}$

$t_{1/2}=990s$

Hence, the correct option is $\text{A}.$