Question

What would the unit be if you calculate the rate when A= 0.30 M and b= 0.30 M. I have the calculation done right and its 1.57 x 10 to the -3 but I don't know the unit

Answer 1

I think that you need more information then what you are providing for someone to be of any help.

Answer 2

Devron is right. You need to know the order of the reaction. I copied the following from Wikipedia.
<b>For order zero, the rate coefficient has units of mol·L−1·s−1 (or M·s−1)
For order one, the rate coefficient has units of s−1
For order two, the rate coefficient has units of L·mol−1·s−1 (or M−1·s−1)
And for order three, the rate coefficient has units of L2·mol−2·s−1 (or M−2·s−1)</b>