What is the correct formula for potassium sulfite
The correct answer and explanation is:
Correct Answer: The formula for potassium sulfite is K₂SO₃.
Explanation:
Potassium sulfite is an ionic compound made up of potassium ions and sulfite ions. To write its correct chemical formula, it is important to understand the charges of each ion:
- Potassium (K) is an alkali metal from Group 1 of the periodic table. It loses one electron to form a K⁺ ion, which carries a +1 charge.
- Sulfite is a polyatomic ion with the formula SO₃²⁻. It carries a -2 charge.
In an ionic compound, the total positive charge must balance the total negative charge. The sulfite ion has a 2– charge, and each potassium ion has a 1+ charge. To balance the charges, two potassium ions are needed for every one sulfite ion:
- 2 K⁺ ions → total charge = +2
- 1 SO₃²⁻ ion → total charge = –2
These charges cancel out, creating a neutral compound. So the correct chemical formula becomes:
K₂SO₃
This formula shows that two potassium ions combine with one sulfite ion to form potassium sulfite.
Potassium sulfite is used in some industrial and food applications, particularly as a preservative and in photographic and textile processing. The compound is highly soluble in water and acts as a reducing agent. It is different from potassium sulfate (K₂SO₄), which contains the sulfate ion (SO₄²⁻) rather than sulfite (SO₃²⁻).
In summary, understanding the charges of the ions and ensuring the total positive and negative charges are equal allows for writing the correct formula: K₂SO₃.