1. Write the balanced molecular equation:
3CaCl₂(aq) + 2Na₃PO₄(aq) → Ca₃(PO₄)₂) (s) + 6NaCl(aq)
2. Write the complete ionic equation:
This involves breaking down all soluble ionic compounds into their respective ions:
3Ca²⁺(aq) + 6Cl⁻(aq) + 6Na⁺(aq) + 2PO₄³⁻(aq) → Ca₃(PO₄)₂(s) + 6Na⁺(aq) + 6Cl⁻(aq)
3. Identify and cancel out spectator ions:
Spectator ions are those that appear on both sides of the equation and do not participate in the reaction. In this case, Na⁺ and Cl⁻ are spectator ions:
3Ca²⁺(aq) + 6Cl⁻(aq) + 6Na⁺(aq) + 2PO₄³⁻(aq) → Ca₃(PO₄)₂(s) + 6Na⁺(aq) + 6Cl⁻(aq)
4. Write the net ionic equation:
This equation only includes the ions that directly participate in the reaction:
3Ca²⁺(aq) + 2PO₄³⁻(aq) → Ca₃(PO₄)₂(s)
Therefore, the net ionic equation for the reaction between calcium chloride and sodium phosphate is 3Ca²⁺(aq) + 2PO₄³⁻(aq) → Ca₃(PO₄)₂(s).
