Chapter U6, Problem 12STP

Interpretation Introduction

Interpretation:

The equilibrium concentrations of the starting substances and products needs to be determined.

Concept introduction:

At equilibrium, the rate of formation of product is same as rate of deformation of reactant. Thus, the rate of decrease in the concentration of reactant is equal to the rate of increase in the concentration of product. At this point, there is no change in the concentration of reactant and product takes place.

Answer to Problem 12STP

The correct option is (A).

Explanation of Solution

The given equilibrium reaction is as follows:

${\text{A}}_{\text{2}}\left(g\right)+3{\text{B}}_2\left(g\right)\rightleftharpoons 2{\text{AB}}_3\left(g\right)$

At equilibrium, the rate of change of concentration of product and reactant will be same. When no change in the concentration takes place with time, it is represented by line parallel to time axis. It is after 25 second in the graph.

Now, at 25 sec, the concentration of reactant ${\text{A}}_{\text{2}}\left(g\right)$ is approximately 0.37 M, the concentration of reactant ${\text{B}}_2\left(g\right)$ is approximately 1.1 M and that of product ${\text{AB}}_3\left(g\right)$ is 1.2 M.

Conclusion

Therefore, the correct option is (A).