In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B. 2A3B How many molecules of substance B are produced when 29.8 g of substance A reacts? The molar mass of substance A is 29.2 g/mol. Step 1: Convert the mass of A to moles. moles of A: TOOLS x10y mol Step 2: Convert the number of moles of A to the number of moles of B. moles of B: mol Step 3: Convert the number of moles of B to molecules of B. molecules of B: