Answer to Question #123072 in General Chemistry for Angela

Question

50.0 mL of 0.30 M potassium phosphate is mixed with 150.0 mL of 0.40 M magnesium phosphate. Determine the concentration of each ion in the final solution.

Answer 1

Potassium phosphate is K₃PO₄ while Magnesium phosphate is Mg₃(PO₄)₂

ionic reactions involved are

K₃PO₄ ----> 3K⁺+PO₄^3-

Mg₃(PO₄)₂----> 3Mg²⁺+ 2PO₄^3-

no. of moles of K₃PO₄ = 50* 0.30= 15 mmoles

so according to stiochiometry in ionic reaction

no of moles of K⁺ = 3* 15 = 45 mmoles

while no. of PO₄^3- = 15 mmoles

in case of magnesium phosphate

no of moles of Mg₃(PO₄)₂ = 150* 0.40 = 60 mmoles

according to stiochiometry in ionic reaction

no of moles of Mg²⁺= 3* 60 = 180 mmoles

while for Phosphate ion = 2*60= 120 mmoles

total volume of solution = 50+ 150 mL = 150mL

concentration of K⁺= 45/200 = 0.225 M

concentration of Mg²⁺= 180/200= 0.90 M

concentration of PO₄^3-=(15+120)/200

= 170/200 = 0.85 M