The rate constant of the reaction $A ightarrow B$ is $0.6 imes 10^{-3} ext{ molar per second}$. If the c

Question

The rate constant of the reaction $A ightarrow B$ is $0.6 	imes 10^{-3} 	ext{ molar per second}$. If the concentration of A is $5 	ext{ M}$, then the concentration of B after $20 	ext{ min}$ is:

Accepted Answer

The unit of the rate constant is $	ext{molar per second}$ ($	ext{M s}^{-1}$), which indicates that it is a zero-order reaction.
For a zero-order reaction, the integrated rate equation is:
$[A]_t = [A]_0 - kt$
The amount of reactant $A$ consumed is $kt$. Since the stoichiometry of the reaction is $1:1$, the concentration of product $B$ formed will be equal to the amount of $A$ consumed.
$[B] = kt$
Given data:
$k = 0.6 	imes 10^{-3} 	ext{ M s}^{-1}$
$t = 20 	ext{ min} = 20 	imes 60 	ext{ s} = 1200 	ext{ s}$
Substituting the values into the equation:
$[B] = (0.6 	imes 10^{-3} 	ext{ M s}^{-1}) 	imes 1200 	ext{ s}$
$[B] = 0.6 	imes 1.2 	ext{ M} = 0.72 	ext{ M}$
Therefore, the concentration of $B$ after $20 	ext{ minutes}$ is $0.72 	ext{ M}$.

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