The double replacement reaction of aqueous li3po4 and cas produce a calcium phosphate precipitate and aqueous lithium sulfide. how many grams of ca3(po4)2 will be produced when 1.13 grams of calcium sulfide react with excess lithium phosphate.

First, use the molar mass of calcium sulfide (72.143 g/mol) to find the number of moles of CaS in 1.13 grams:



Now the equation for this reaction is 
Li3PO4 + CaS --> Ca3(PO4)2 + Li2S

but the BALANCED equation is

2Li3PO4 + 3CaS --> Ca3(PO4)2 + 3Li2S

because in this, there is an equal number of every atom.  In the balanced equation, there are 3 moles of CaS for every one mole of Ca3(PO4)2 created, so we change it like this:



The molar mass of Ca3(PO4)2 is 310.1767 g/mol: