What is the percent by mass of potassium (K) in KMnO4?

• A. 25.0%
• B. 15.8%
• C. 5.3%
• D. 39.1%

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the compound, which is potassium permanganate, KMnO\_4.
2. Calculate the molar mass of KMnO\_4 by summing the atomic masses of all atoms in the formula: potassium (K), manganese (Mn), and oxygen (O). Use the atomic masses: K = 39.10 g/mol, Mn = 54.94 g/mol, and O = 16.00 g/mol.
3. Calculate the total molar mass of KMnO\_4 using the formula: \(M_{KMnO_4} = M_K + M_{Mn} + 4 \times M_O\).
4. Determine the percent by mass of potassium in KMnO\_4 using the formula: \(\% \text{K} = \left( \frac{M_K}{M_{KMnO_4}} \right) \times 100\%\).
5. Substitute the values into the formula and perform the division and multiplication to find the percent by mass of potassium.