In a chemical reaction, A and B reacts to form D. C is the intermediate product of this reaction. Percent yield of the reaction A+B->C is 50% and the percent yield of the reaction C->D is 90%. How many moles of D can be produced when 14 moles of A and B react?

Answer 1

The long way:
14 mols A and 14 mols B will produce 14*0.50 = 7 mols C.
Then C will produce 7*0.9 = 6.3 mols D.

The short way:
overall yield is 0.5*0.9 = 0.45 or 45%.
14*0.45 = 6.3