What is the correct formula for potassium sulfite? A) KHSO3 B) K2SO3 C) K₂SO4 D) KHSO
The correct answer and explanation is:
Correct Answer: B) K₂SO₃
The correct formula for potassium sulfite is K₂SO₃. This is because potassium sulfite is composed of potassium ions and sulfite ions. To write its formula correctly, you need to understand the charges of these ions and balance them properly.
Potassium is a metal from Group 1 of the periodic table. All Group 1 elements form ions with a +1 charge, so the potassium ion is K⁺.
Sulfite is a polyatomic ion with the formula SO₃²⁻, and it has a -2 charge.
To make a neutral compound, the positive and negative charges must balance. Since each potassium ion carries a +1 charge, and the sulfite ion carries a -2 charge, two potassium ions are needed to balance one sulfite ion:
- 2 K⁺ ions give a total charge of +2
- 1 SO₃²⁻ ion gives a charge of -2
When these ions combine, the charges cancel out, resulting in a neutral compound. Therefore, the correct chemical formula is:
K₂SO₃
This shows that two potassium ions combine with one sulfite ion.
The other choices are incorrect for the following reasons:
- A) KHSO₃ is potassium bisulfite or potassium hydrogen sulfite, which contains the hydrogen sulfite ion (HSO₃⁻), not sulfite (SO₃²⁻).
- C) K₂SO₄ is potassium sulfate, which contains the sulfate ion (SO₄²⁻), not sulfite (SO₃²⁻).
- D) KHSO is not a valid compound; it does not represent a known ion combination or stable compound in chemistry.
Understanding ion charges and balancing them correctly is essential when writing formulas for ionic compounds like potassium sulfite.