What is the percent by mass of potassium (K) in K3Fe(CN)6?

• A. 25.53%
• B. 21.88%
• C. 35.62%
• D. 16.96%

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the compound: K\_3Fe(CN)\_6. This means the compound contains 3 potassium (K) atoms, 1 iron (Fe) atom, 6 carbon (C) atoms, and 6 nitrogen (N) atoms.
2. Find the atomic masses of each element from the periodic table: potassium (K), iron (Fe), carbon (C), and nitrogen (N). These values are usually given in atomic mass units (amu) or grams per mole (g/mol).
3. Calculate the molar mass of the entire compound by summing the contributions of each element: multiply the atomic mass of each element by the number of atoms of that element in the formula, then add all these values together. Mathematically, this is: \(\text{Molar mass} = 3 \times M_K + 1 \times M_{Fe} + 6 \times M_C + 6 \times M_N\).
4. Calculate the total mass of potassium in one mole of the compound by multiplying the atomic mass of potassium by 3 (since there are 3 potassium atoms): \(\text{Mass of K} = 3 \times M_K\).
5. Find the percent by mass of potassium by dividing the total mass of potassium by the molar mass of the compound and multiplying by 100 to convert to a percentage: \(\% \text{K} = \left( \frac{3 \times M_K}{\text{Molar mass of } K_3Fe(CN)_6} \right) \times 100\).