Final answer:
The formula for plumbous phosphate is Pb3(PO4)2, which results from balancing the charges of plumbous (Pb2+) with the phosphate ion (PO43-). Formula mass can be calculated by adding the atomic masses of all atoms in the compound as demonstrated with calcium phosphate, Ca3(PO4)2.
Step-by-step explanation:
The formula for plumbous phosphate is quite specific because it involves the plumbous (Pb2+) ion. The correct formula for this compound is Pb3(PO4)2. Plumbous indicates the lead ion with a +2 oxidation state, and phosphate is the polyatomic ion (PO4)3−. When creating the formula for an ionic compound, you must balance the total positive and negative charges. Lead (Pb) has a +2 charge in this context, and phosphate has a –3 charge. As such, you need three lead ions to balance two phosphate ions, for a neutral compound.
To calculate the formula mass of a compound like calcium phosphate (Ca3(PO4)2), you would add together the atomic masses of all atoms within the formula, which would include three calcium atoms (Ca2+), two phosphorus atoms (P), and eight oxygen atoms (O). This ensures you have the correct mass for one formula unit of calcium phosphate.