For the following reaction, it is found that doubling the amount of A causes the reaction rate to quadruple. Doubling the amount of B has absolutely no effect on the rate.

What is the best rate law equation for this reaction?

A + B 2C

R = k[ A ]²

Explanation:

What we are being asked is to determine the exponents in the equation:

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

where R = reaction rate of the chemical reaction, k is the reaction constant, [A ][B] are the concentrations, and a and b are exponents.

Now the reaction has b = 0 since changing the concentration of B has no effect on the rate.

So,

R = k [ A ]^a

Doubling the amount of A, quadruples the reaction. Therefore a = 2, and the best law equation is R = k[ A ]²