Question

The rate constant of a reaction is 0.0693 $mi{n}^{-1}$. Starting with 10 mol, the rate of the reaction after 10 min is:

• A. 0.0693 mol $mi{n}^{-1}$
• B. 0.0693 $\times$ 2 mol $mi{n}^{-1}$
• C. 0.0693 $\times$ 5 mol $mi{n}^{-1}$
• D. 0.0693 $\times 5^2$ mol $mi{n}^{-1}$

Answer 1

The correct option is C 0.0693 $\times$ 5 mol $mi{n}^{-1}$

As we know,
for a first order reaction,
$t_{1/2}=\frac{0.693}{k}=\frac{0.693}{0.0693}=10min$
Reactant after 10 min = 5 mol
Rate $\left(\frac{dx}{dt}\right)=k\left[A\right]=0.0693\times 5molmi{n}^{-1}$