Explain why the rate of a ????

Question

Explain why the rate of a simple chemical reaction such as
NO(g) + ½ O2(g) = NO2(g)
is likely to be most rapid at the beginning of the reaction.

plz asap!!!!

Answer 1

Most, but not all chemical reactions are dependent on the concentrations (amount) of the reactants (starting materials). At the beginning of a reaction, there are more reactant particles present to react. As the reactions proceeds and converts the reactants into products, the concentration or amount of reactants becomes smaller and the reaction slows down.

Answer 2

While it appears as a simple reaction, it is really a two step process. The first step involves combining NO with O2 to form the dimer N2 O2. In the next step N2O2 combines with O2 to form NO2. This is a much slower reaction. It has something to do with the concentration of the reactants at that stage of the process.

For much more info check out this link: http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch22/react.html