Question

In determining the reaction velocity for the reaction A + 2B ⇌AB2

Why must the concentration of the molecules?

Answer 1

The reaction velocity is determined by the concentrations of the reactants. Similarly, rate of reaction equals:

r = k[A]^a[B]^b

where r - rate of reaction, k - rate constant, [A] and [B] - concentrations of A and B, a and b - orders of the reaction.