Question

2Na3PO4(aq)+3 Ba(NO3)2(aq)---->Ba3(PO4)2(s)+6NaNO3(aq)
a solution containing 3.50g of Na3PO4 is mixed with a solution containing 6.40g of Ba(NO3)2 how many grams of product can be formed?
and if the above reaction resulted in 3.659 g of white powder, what is the percent yeild for the reaction?

Answer 1

This is a limiting reagent problem. You know that because amounts for BOTH reactants are given. I solve these, the long way by the way, by solving for moles product using the first reactant (ignore the second one), then the second reactant (ignore the first one). You will obtain two answers for the product and both can't be right, of course. The correct answer in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent. Here is a link that will show you exactly how to solve for the product. It also shows, at the end of the worksheet, how to determine percent yield.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Post you work if you get stuck.