A compound contains 27.0% sulfur and 73.0% oxygen by mass. What is the empirical formula of this compound?

• A. SO_2
• B. SO_3
• C. S_2O_2
• D. S_2O_3

Answer: (B)

Verified step by step guidance

1. Step 1: Assume a 100 g sample of the compound so that the mass of sulfur (S) is 27.0 g and the mass of oxygen (O) is 73.0 g.
2. Step 2: Convert the masses of each element to moles by dividing by their atomic masses: use 32.07 g/mol for sulfur and 16.00 g/mol for oxygen. Calculate moles of S as \(\frac{27.0}{32.07}\) and moles of O as \(\frac{73.0}{16.00}\).
3. Step 3: Determine the simplest whole number mole ratio by dividing both mole values by the smaller of the two mole amounts obtained in Step 2.
4. Step 4: If the mole ratio is not a whole number, multiply both ratios by the smallest integer that converts them into whole numbers (e.g., 2, 3, or 4).
5. Step 5: Write the empirical formula using the whole number mole ratios as subscripts for sulfur and oxygen, respectively.