Chemical Kinetics

Trichloroethanoic acid can be used to precipitate proteins from plasma. It is readily decarboxylated in aqueous solution according to the following reaction:
CCl3COOH (aq) → CHCl3 (aq) + CO2 (g)
The reaction kinetics were monitored by measuring the volume V of CO2 released as a function of time:
A plot of ln(V) versus time gave a straight line graph with a negative slope of -2.8 x 10-4 s-1
(i) What is the rate law for this reaction. Give a reason for your answer.
(ii) Determine the rate constant for this reaction.
(iii) Determine the half-life of the reaction.
(iv) If the initial concentration of CCl3COOH is 0.1M, calculate the time taken for this initial concentration of CCl3COOH to fall by 25 %.