Final answer:
To determine the value of the equilibrium constant Kc from a concentration vs. time plot, use the concentrations of the reactants and products at equilibrium. Divide the concentration of the products raised to their coefficients by the concentration of the reactants raised to their coefficients.
Step-by-step explanation:
To determine the value of the equilibrium constant Kc from the concentration vs. time plot, you need to examine the concentration of the reactants and products at equilibrium. The equilibrium constant (Kc) is calculated by dividing the concentration of the products raised to their stoichiometric coefficients by the concentration of the reactants raised to their stoichiometric coefficients. In this case, Kc = [B]^1 / [A]^3, since the coefficients in the balanced equation are 1 and 3 for B and A, respectively.
Looking at the concentration vs. time plot, you need to find the concentrations of B and A at equilibrium. The equilibrium concentrations can be determined by the concentration values reached when the graph levels off, indicating that the reaction has reached equilibrium. Once you have these equilibrium concentrations, plug them into the equation for Kc to calculate its value.