Characterize a system at chemical equilibrium with respect to each of the following: 

a. The rates of the forward and reverse reactions 

b. The overall composition of the reaction mixture

For a general reaction 3A(g) + B(g) → 2C(g), if one starts an experiment with only reactants present, show what the plot of concentrations of A, B, and C versus time would look like. Also sketch the plot illustrating the rate of the forward reaction and rate of the reverse reaction versus time.