The rate of a first order reaction is 0.04 mol litre^-1 s^-1 at 10 minutes and 0.03 mol litre^-1 s^-1 at 20 minutes after initiation. Find the half-life of the reaction.

A hydrogenation reaction is carried out at 500 K. If the same reaction is carried out in the presence of a catalyst at the same rate, the temperature required is 400 K. Calculate the activation energy of the reaction if the catalyst lowers the activation barrier by 20 kJ mol^-1.

The rate constant for an isomerisation reaction, A $$\to$$ B is 4.5 $$\times$$ 10^-3 min^-1. If the initial concentration of A is 1 M, calculate the rate of the reaction after 1 h.

The rate constant of a reaction is 1.5 $$\times$$ 10⁷ s^-1 at 50^oC and 4.5 $$\times$$ 10⁷ s^-1 at 100^oC. Evaluate the Arrhenius parameters A and E_a.