The rate of a first-order reaction is directly proportional to the concentration of one reactant. The mathematical expression for the rate of a first-order reaction is:
k[A]where:
k is the rate constant
[A] is the concentration of the reactant.
The rate equation can be expressed as:
Rate =k[A]Given that a graph of rate versus concentration, the slope of this graph for a first-order reaction would be equal to the rate constant,
k, because the rate is directly proportional to the concentration
[A] :
Slope
=kTherefore, if the slope for the graph of rate versus concentration is
2.5×10−3, then the value of the rate constant for the first-order reaction is:
k=2.5×10−3 time −1So, the correct answer is:
Option A
2.5×10−3 time
−1