The reaction between Na₂HPO₄ (sodium hydrogen phosphate) and CaCl₂ (calcium chloride) is a double displacement reaction that produces a precipitate.

Here's the balanced chemical equation:

Na₂HPO₄ (aq) + CaCl₂ (aq) → CaHPO₄ (s) + 2NaCl (aq)

Here's what happens:

* Reactants:

* Na₂HPO₄ is dissolved in water, forming sodium and hydrogen phosphate ions (Na⁺ and HPO₄²⁻).

* CaCl₂ is also dissolved in water, forming calcium and chloride ions (Ca²⁺ and Cl⁻).

* Products:

* CaHPO₄ (Calcium hydrogen phosphate) precipitates out of the solution as a white solid.

* NaCl (Sodium chloride) remains dissolved in the solution.

Explanation:

The reaction occurs because calcium ions (Ca²⁺) from CaCl₂ combine with hydrogen phosphate ions (HPO₄²⁻) from Na₂HPO₄ to form the insoluble compound CaHPO₄. This results in the precipitation of calcium hydrogen phosphate, leaving sodium chloride in the solution.

Note: The solubility of CaHPO₄ depends on the pH of the solution. It's generally considered slightly soluble, but in the presence of excess Ca²⁺ ions, it can form a more insoluble calcium phosphate compound (Ca₃(PO₄)₂).