You wish to determine the molarity of K^+ ions in a 50.0 ml sample of K3PO4. You completely react the potassium phosphate with calcium nitrate. Upon completion you obtain 0.542 g of calcium phosphate. Determine the molarity of K^+ ions in the original solution.
2K3PO4(aq) + 3Ca(NO3)2 (aq) = 6KNO3(aq) + Ca3(PO4)2(s)