Question

The rate constant of the reaction $A\to B$ is $0.6\times {10}^{-3}\text{M/s}$. If the concentration of $A$ is $5\text{M}$, then concentration of $B$ after 20 minutes is :-

• A. $0.36\text{M}$
• B. $0.72\text{M}$
• C. $1.08\text{M}$
• D. $3.60\text{M}$

Answer 1

The correct option is B $0.72\text{M}$

The units of k are the same as the units of the rate of change of concentration of the reactant $\frac{dA}{dt}$, which means that this is a zero order reaction. The integrated form of the rate equation is:
$\left[A\right]=\text{kt}$
$=0.6\times {10}^{-3}\times 20\times 60$
$\left[A\right]=0.72\text{M}$