In an aqueous solution of Ca₃(PO₄)₂, calcium phosphate, the compound will undergo ionization to release its constituent ions. The relevant chemical species present are calcium ions (Ca²⁺), hydrogen phosphate ions (HPO₄²⁻), and calcium phosphate (Ca₃(PO₄)₂). Given that the phosphate ion (PO₄³⁻) is a weak base, it can accept a proton (H⁺) to form the hydrogen phosphate ion (HPO₄²⁻).
The correct representation of the chemical species in decreasing order of their concentrations is:
b) HPO₄²⁻, Ca₃(PO₄)₂, Ca²⁺
Step-by-step explanation:
Hydrogen phosphate ions HPO₄²⁻ are formed by the partial ionization of Ca₃(PO₄)₂ in water. Since the phosphate ion is a weak base, it can accept a proton to form HPO₄²⁻.
Ca₃(PO₄)₂ is a sparingly soluble salt, and its ionization is limited. Therefore, the concentration of Ca₃(PO₄)₂ will be lower compared to HPO₄²⁻.
Calcium ions (Ca²⁺) are released into the solution as Ca₃(PO₄)₂ ionizes, but their concentration will be less than that of HPO₄²⁻.
So, the correct answer is option:
b) HPO₄²⁻, Ca₃(PO₄)₂, Ca²⁺