Describe the differences between the first, second and zero order reactions.

First order reactions have a rate proportional to the concentration of one reactant, while second order reactions have a rate proportional to the concentration of two reactants. Zero order reactions have a constant rate independent of reactant concentration.

First order reactions involve the decay of a single reactant, and their rate is proportional to the concentration of that reactant. This means that as the concentration of the reactant decreases, so does the rate of the reaction. Examples of first order reactions include radioactive decay and the breakdown of hydrogen peroxide.

Second order reactions involve the collision of two reactants, and their rate is proportional to the concentration of both reactants. This means that as the concentration of either reactant decreases, the rate of the reaction decreases. Examples of second order reactions include the reaction between hydrogen and iodine, and the reaction between nitric oxide and oxygen.

Zero order reactions have a constant rate that is independent of the concentration of the reactants. This means that the rate of the reaction does not change as the concentration of the reactants changes. Examples of zero order reactions include the breakdown of aspirin and the oxidation of ethanol.