Hint: Remember that reactions happen in

moles. So figure out the moles that reacted
then use the molarity formula to continue
solving the problem.
What volume of 0.699 M K3PO4 is required
to react with 68 mL of 0.661 MMgCl2 accord-
ing to the equation
2K3PO4 + 3MgCl2 ! Mg3(PO4)2 + 6KCl
Answer in units of mL

1. mols MgCl2 = M x L = ?

2. Use the coefficients in the balanced equation to convert mols MgCl2 to mols K3PO4.
3. Now M K3PO4 = mols K3PO4/L K3PO4. You know mols and M, solve for L and convert to mL if that is required.