If the rates of forward and backward reaction in a chemical reaction become equal, the reaction is said to be in equilibrium state. At this state, reactants react to form products and products are converted into the same amount of reactants. Thus, it seems that the reaction has stopped, but the reaction keeps on going in both the directions at equal rates.

So, at Equilibrium r f = r b

where r f = Rate of forward reaction

and r b = Rate of backward reaction

Equilibrium constant is the ratio of the rate constant of forward reaction to rate constant of back ward reaction Kc =

For the reaction A → B + C, the following data were obtained at 300º C.

Experiment [A], mol L –1 Rate, mol –1 h –1

1 0.170 0.05

2 0.340 0.10

3 0.680 0.20

The equilibrium constant for the reaction is 0.50 mol L –1 Assuming that the reaction proceeds by a one step mechanism.

(i) What is order of reaction for forward reaction –