1.Zero order reaction? 2. First order …

A reaction is said to be of zero order if its rate is independent of the concentration of the reactants, i.e., the rate is proportional to the zeroth power of the concentration of the reactants.

For the reaction A → products to be of zero order, 

Rate=- \frac{d[A]}{dt} = k[A]^0

First Order Reaction When the rate of the reaction depends on the first power of the reactant concentration in the rate equation, then the reaction is said to follow first order kinetics. The change in the concentration of only one reactant will affect the rate of the reaction.

For example consider the reaction :

A+B→productsA+B→products

For the first order reaction : Rate of the reaction = k[A] 

Therate of the reaction depends on the concentration of only A. Change in concentration of B is not going to affect the rate of the reaction. The rate of the reaction is zero order with respect to B. 

Therate of the reaction can otherwise also be written as :

Rate of the reaction = k[A][B]o