A compound is found to be 30.45% nitrogen (N) and 69.55% oxygen (O) by mass. If 1.63 g of this compound occupy 389 mL at 0.00°C and 775 mm Hg, what is the empirical formula of the compound?

• A. N2O4
• B. N2O
• C. NO2
• D. NO

Answer: (C)

Verified step by step guidance

1. Convert the percentage composition of nitrogen and oxygen to grams assuming a 100 g sample. This means you have 30.45 g of nitrogen and 69.55 g of oxygen.
2. Convert the masses of nitrogen and oxygen to moles using their respective molar masses. The molar mass of nitrogen (N) is approximately 14.01 g/mol and for oxygen (O) is approximately 16.00 g/mol.
3. Calculate the mole ratio of nitrogen to oxygen by dividing the number of moles of each element by the smallest number of moles calculated in the previous step.
4. Use the mole ratio to determine the empirical formula. The empirical formula is the simplest whole number ratio of moles of each element in the compound.
5. Verify the empirical formula by considering the given conditions (mass, volume, temperature, and pressure) to ensure it aligns with the molecular formula, if needed.