Question

Supply a formula to match the name potassium permanganate

Express your answer as a chemical formula.
a) K₂MnO₄
b) KMnO₄
c) K(MnO₄)₂
d) K₃MnO₄

Answer 1

b) KMnO₄

The formula for potassium permanganate is KMnO₄, as it consists of one potassium ion (K⁺) and one permanganate ion (MnO₄⁻).

Step-by-step explanation:

The correct formula for potassium permanganate is KMnO₄. The permanganate anion has the formula MnO₄⁻, and when it forms an ionic compound with the potassium ion (K⁺), each potassium ion balances one of the negative charges on the MnO₄⁻ ion. Therefore, the correct formula that matches the name potassium permanganate is KMnO₄.

For the ionic compounds between the permanganate ion and other cations, we would have:

• For potassium ion (K⁺): KMnO₄ (potassium permanganate)
• For calcium ion (Ca²⁺): Ca(MnO₄)₂ (calcium permanganate), because one calcium ion balances two negative charges.
• For iron(III) ion (Fe³⁺): Fe(MnO₄)₃ (iron(III) permanganate), because one iron(III) ion balances three negative charges.