A Dissociation of calcium phosphate Ca PO s 3 Ca2 aq 2 PO43

(A) Dissociation of calcium phosphate Ca (PO): (s) 3 Ca+2 (aq) + 2 PO4-3 (aq) PINK p Observation upon mixing calcium nitrate with sodium phosphate tc GENT ADDED OBSERVATION DIRECTION OF SHIFT REASON HCI

Solution

Q1: WHICH direction does the equilibrium shift when HCL is added and the REASON WHY?

Ca₃(PO₄)₂ (s) <---------> 3 Ca²⁺ (aq) + 2PO₄^3- (aq)

Purple Pink

Answer: The solution turns purple and equilibrium shifts to left.

Adding HCl will dissociate Ca₃(PO₄)₂ into Ca²⁺ and PO₄^2- ions. This increases the concentration of ions on the right there by pushing the equilibrium to left.

Ca₃(PO₄)₂ (S)+ 6HCl -----------> 3Ca²⁺(aq) + 2H₃PO₄(aq)

The phosphate ions (basic in nature) on the left react with hydrogen ions (from HCl)_, there by reducing the phosphate ion concentraion on the right. According to Lechatlier\'s principle inrder to balance the loss of phosphate ions on the right, equilibrium is shifted to the right. And since the euilibrium shifts to right, the solution turns pink.

Q2: WHICH direction does the equilibrium shift when HCl+NaOH is added and the REASON WHY?

Answer: The solution turns pink and the equilibrium shifts to right.

Adding HCl and NaOH will result in consuming the Ca²⁺ and PO₄^2- ions (on the right) in form of the following reactions. This decreases the concentration of ions on the right, pushing the equilibrium to right.

Ca²⁺ + NaOH ---------> Ca(OH)₂ +Na⁺

PO₄^2- + HCl ---------> H₃PO₄ + Cl^-