Answer
You need the chemical equation and the molar mass of A and B, to determine the amount of product.
Work Step by Step
If we have the molar mass of A and B, we can determine the number of moles of A and B we reacted. Furthermore, if we have the chemical equation, we may determine whether A or B is the limiting reactant as well as determine how many moles of product is formed through mole ratios determined from the coefficients of the balanced chemical equation.