# What are the formula, molar mass, and color of potassium permanganate?

Jun 27, 2016

See explanation.

#### Explanation:

Potassium permanganate is the potassium salt of the permanganate anion, ${\text{MnO}}_{4}^{-}$.

Since potassium form $1 +$ cations and the permanganate anion carries a $1 -$ charge, you can say that one formula unit of potassium permanganate contains

• one potassium cation, $1 \times {\text{K}}^{+}$
• one permanganate anion, $1 \times {\text{MnO}}_{4}^{-}$ Therefore, the chemical formula for potassium permanganate will be ${\text{KMnO}}_{4}$.

The molar mass of potassium permanaganate can be found by adding the molar masses of its constituent elements.

You will thus have

${M}_{\text{M KMnO"_ 4) = M_ ("M K") + M_ ("M Mn") + 4 xx M_("M O}}$

Use the periodic table to write

M_("M KMnO"_4) = "39.0983 g mol"^(-1) + "54.93085 g mol"^(-1) + 4 xx "15.9994 g mol"^(-1)

M_ ("M KMnO"_4) = "158.027 g mol"^(-1)

Finally, potassium permanganate has a dark gray - bronze - purplish color in the solid state and a magenta color in solution. 