Question

A second order reaction of the type A + B → P was carried out in a solution with initial concentrations of 0.075 and 0.050 mol/L for A and B, respectively. After one hour, the concentration of B decreased to 0.020 mol/L. The reaction rate is expressed as

v = k [A][B]

Calculate the rate constant of this reaction.

Answer 1

The rate constant (k) calculation for a second-order reaction requires knowing both reactants' concentrations and the reaction rate at the same time; with only the initial concentrations and the change in one reactant's concentration, k cannot be determined.

Step-by-step explanation:

To calculate the rate constant (k) for the second order reaction A + B → P, given the initial concentrations and the change in concentration of one reactant (B) over a period of time, we can use the rate law expression v = k [A][B].

We are given the initial concentrations, [A] = 0.075 mol/L and [B] = 0.050 mol/L, and that [B] decreased to 0.020 mol/L after one hour.

The reaction rate (v) at this time will be determined by the change in concentration of B divided by the elapsed time. We can solve for the rate constant k if we know the reaction rate and the concentrations of A and B at the same time.

However, without the concentration of A at one hour, or a reaction rate, we cannot solve for k with the given information.