Question

What is the empirical formula of a compound containing 40% sulfur and 60% oxygen by mass?

• A. \( \text{SO}_2 \)
• B. \( \text{SO}_3 \)
• C. \( \text{S}_2\text{O}_3 \)
• D. \( \text{SO} \)

Hint:

Remember: To determine the empirical formula, convert the mass percentages of elements to moles, find the simplest ratio, and write the formula using whole numbers.

Answer 1

The Correct Option is A

Step 1: Assume a total mass of the compound Assume the total mass of the compound is 100 g. This allows us to easily calculate the mass of sulfur and oxygen. \[ \text{Mass of sulfur} = 40 \, \text{g}, \quad \text{Mass of oxygen} = 60 \, \text{g} \] Step 2: Convert the masses of sulfur and oxygen to moles The molar mass of sulfur (\( \text{S} \)) is 32 g/mol, and the molar mass of oxygen (\( \text{O} \)) is 16 g/mol. \[ \text{Moles of sulfur} = \frac{40 \, \text{g}}{32 \, \text{g/mol}} = 1.25 \, \text{mol} \] \[ \text{Moles of oxygen} = \frac{60 \, \text{g}}{16 \, \text{g/mol}} = 3.75 \, \text{mol} \] Step 3: Find the ratio of moles of sulfur to oxygen The ratio of moles of sulfur to oxygen is: \[ \text{Ratio} = \frac{1.25}{1.25} : \frac{3.75}{1.25} = 1 : 3 \] Step 4: Write the empirical formula The empirical formula is the simplest whole-number ratio of atoms in the compound. The ratio of sulfur to oxygen is 1:2, so the empirical formula is \( \text{SO}_2 \). Answer: Therefore, the empirical formula of the compound is \( \text{SO}_2 \). So, the correct answer is option (1).