Question

The concentration of a reactant X decreases from 0.1 M to 0.025 M in 40 minutes. If the reaction follows I order kinetics, the rate of the reaction when the concentration of X is 0.01 M will be

• A. $3.47\times {10}^{-4}Mmi{n}^{-1}$
• B. $1.73\times {10}^{-4}Mmi{n}^{-1}$
• C. $1.73\times {10}^{-5}Mmi{n}^{-1}$
• D. $3.47\times {10}^{-5}Mmi{n}^{-1}$

Answer 1

The correct option is A $3.47\times {10}^{-4}Mmi{n}^{-1}$

40 minutes $\equiv \frac{1}{4}$ the initial concentration. So half-life is 20 minutes
$\frac{dx}{dt}=K[R{]}^1=\frac{0.693\times (0.01{)}^1}{20}=3.47\times {10}^{-4}Mmi{n}^{-1}$