rate of reaction

Question

2A + B → C + D

The rate of disappearance of A in the reaction above is - d[A]/dt = K[A][B]2

What happens to the rate of appearance of C if the concentration of A is doubled and that of B is tripled?

Answer 1

Knowing the rate law, you can plug in hypothetical values and see what happens.  For example, since you're doubling the concentration of A and tripling that of B, you could do this:

k[2][3]^2 = 18.  So the rate would be 18 times faster.  Thus, the appearance of C would be 18 times faster than if the concentrations of A & B were equal to one.