What is the empirical formula for a compound that is 36.1% Ca and 63.9% Cl by mass?

• A. CaCl2
• B. Ca2Cl
• C. Ca2Cl3
• D. CaCl

Answer: (A)

Verified step by step guidance

1. Step 1: Assume you have 100 grams of the compound, so the mass of calcium (Ca) is 36.1 grams and the mass of chlorine (Cl) is 63.9 grams.
2. Step 2: Convert the masses of each element to moles by dividing by their respective atomic masses: use 40.08 g/mol for Ca and 35.45 g/mol for Cl. Calculate moles of Ca as \(\frac{36.1}{40.08}\) and moles of Cl as \(\frac{63.9}{35.45}\).
3. Step 3: Determine the simplest whole number mole ratio by dividing both mole values by the smaller number of moles obtained in Step 2.
4. Step 4: If the mole ratio is not a whole number, multiply both ratios by the smallest factor that converts them into whole numbers (e.g., 2, 3, 4, etc.).
5. Step 5: Write the empirical formula using the whole number mole ratios as subscripts for each element, with Ca and Cl in the order given.