If you dissolve 236.5 g of (NH4)3PO4 and 166.9 g of K3PO4 in enough water to make the volume of the solution 505.0 mL What is the molarity of ammonium ions and phosphate ions?
mols (NH4)3PO4 = grams/molar mass = ?
mols NH4^+ = 3x that.
mols PO4^3- = 1x that.
mols K3PO4 = grams/molar mass = ?
mols PO4^3- = 1x that.
volume is 0.505L
M NH4^+ = mols NH4^+/L solution
M PO4^3- = total mols PO4^3-/L solution.
Note: total mols PO4^3- = mols PO4^3- from (NH4)3PO4 + mols PO4^3- from K3PO4.