The time for half life period of a certain reaction A $$\to$$ products is 1 hour. When the initial concentration of the reactant ‘A’, is 2.0 mol L^–1, how much time does it take for its concentration to come from 0.50 to 0.25 mol L^–1 if it is a zero order reaction ?

The half life period of a first order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be (log 2=0.301) :

For a reaction $${1 \over 2}A \to 2B$$ rate of disappearance of ‘A’ is related to the rate of appearance of ‘B’ by the expression

The energies of activation for forward and reverse reactions for A₂ + B₂ $$\leftrightharpoons$$ 2AB are 180 kJ mol⁻¹ and 200 kJ mol⁻¹ respectively. The presence of catalyst lowers the activation energy of both (forward and reverse) reactions by 100 kJ mol⁻¹. The enthalpy change of the reaction ( A₂ + B₂ $$\to$$ 2AB) in the presence of catalyst will be (in kJ mol⁻¹)