What is the chemical name of Hg2SO4 using the new method?
A. mercurous sulfate
B. mercury (1) sulfate
C. mercury (II) sulfate
D. mercurous sulfite
The correct answer and explanation is :
The correct answer is: B. mercury (I) sulfate
Explanation (300 words):
To determine the correct chemical name for Hg₂SO₄, we need to follow the IUPAC nomenclature guidelines using the Stock system, also referred to as the “new method.”
- Break down the formula:
- Hg = Mercury
- SO₄ = Sulfate ion, which carries a -2 charge
- The formula contains two mercury atoms and one sulfate ion.
- Identify the oxidation state of mercury:
The sulfate ion has a charge of -2. For the entire compound to be electrically neutral, the combined charge of the two mercury atoms must be +2.
Therefore, each mercury atom must have a +1 oxidation state: $$
2 \times (+1) + (-2) = 0
$$ - Naming according to the Stock system:
- In the Stock system, we write the name of the metal, followed by its oxidation state in Roman numerals in parentheses, then the name of the anion.
- The oxidation state of each mercury atom is +1, so the metal part becomes mercury(I).
- SO₄ is the sulfate ion.
- Thus, the correct name is: mercury(I) sulfate
- Why not the other options?
- A. mercurous sulfate: This is the old naming system; “mercurous” refers to Hg⁺ (mercury with +1 charge), but it is not the Stock system.
- C. mercury(II) sulfate: This would be HgSO₄, not Hg₂SO₄.
- D. mercurous sulfite: Incorrect anion (sulfite is SO₃²⁻), and uses the outdated naming format.
Summary:
Hg₂SO₄ contains mercury in the +1 oxidation state and the sulfate ion. Using the Stock system, the correct name is mercury(I) sulfate.