What is the name for Pb(SO3)2?
The Correct Answer and Explanation is:
The correct name for Pb(SO₃)₂ is lead(IV) sulfite.
Explanation
To determine the correct name of Pb(SO₃)₂, we need to understand both the cation (positive ion) and the anion (negative ion) involved, along with their respective charges.
1. Identify the anion:
The chemical formula SO₃²⁻ represents the sulfite ion. Sulfite is a polyatomic ion consisting of one sulfur atom and three oxygen atoms, with an overall charge of 2−. Since there are two sulfite ions in the formula, the total negative charge is:2×(−2)=−42 \times (-2) = -42×(−2)=−4
2. Determine the oxidation state of lead:
In this compound, Pb (lead) must balance the total negative charge of −4. Therefore, the lead ion must have a +4 charge to neutralize the two sulfite ions:Total charge from Pb=+4\text{Total charge from Pb} = +4Total charge from Pb=+4
This means lead is in the +4 oxidation state, and in nomenclature, we indicate the oxidation state using Roman numerals in parentheses. So, Pb⁴⁺ is named as lead(IV).
3. Combine the cation and anion names:
Now we can write the full name of the compound:
- Cation: Lead(IV)
- Anion: Sulfite
So, Pb(SO₃)₂ is named lead(IV) sulfite.
4. Common mistakes to avoid:
A frequent mistake is calling it “lead(II) sulfite” by assuming lead always has a +2 charge. However, that would result in an unbalanced formula. If lead were +2, only one sulfite ion would be needed to balance the charges, giving PbSO₃, not Pb(SO₃)₂.
Thus, the correct and complete IUPAC name is lead(IV) sulfite, accurately reflecting the compound’s composition and charge balance.
