Question

In a first-order reaction $A\to B,$ if k is rate constant and initial concentration of the reactant A is 0.5 M then the half-life is:

• A. $\frac{\ell n2}{K}$
• B. $\frac{0.639}{0.5K}$
• C. $\frac{log2}{K}$
• D. $\frac{log2}{K\sqrt{0.5}}$

Answer 1

The correct option is A

$\frac{\ell n2}{K}$

$t_{\frac{1}{2}}$ for a first order reaction $=\frac{0.639}{K}=\frac{2.303lo{g}_{10}2}{K}=\frac{\ell n2}{K}$