Distinguish between 'rate expression' and 'rate constant' of a reaction.

Explanation

Rate of reaction can be expressed in termed of the concentration of various species. In general, the higher concentration of the reactant, the faster of the reaction. The chemical reaction of rate of reaction is `aA + bB to"Product"`
The rate expression has the form is rate`= k [A]^m [B]^n`
Where k is called the rate constant. A very small value fork means a very slow reactioh. The unit of the rate constant is depends on the total order of the reaction.