What is the correct formula for mercury(II) phosphate?

The correct formula for mercury(II) phosphate is represented as Hg3(PO4)2. This is derived from understanding the charge of mercury and the phosphate ion. Mercury(II) indicates that mercury has a +2 oxidation state. The phosphate ion (PO4) has a -3 charge.

To balance the charges, we need three mercury ions to provide a total charge of +6 (3 × +2) and two phosphate ions, which contribute a total charge of -6 (2 × -3). This results in a neutral compound, satisfying the requirement for a stable ionic compound.

Thus, the formula Hg3(PO4)2 accurately represents the composition of mercury(II) phosphate, with three mercury atoms and two phosphate groups.