What is the mass percent of oxygen in C2H6O (ethanol)?

• A. 52.1%
• B. 34.7%
• C. 43.4%
• D. 16.0%

Answer: (B)

Verified step by step guidance

1. Identify the molecular formula of ethanol, which is C\_2H\_6O, meaning it contains 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom.
2. Find the atomic masses of each element: Carbon (C) = 12.01 g/mol, Hydrogen (H) = 1.008 g/mol, Oxygen (O) = 16.00 g/mol.
3. Calculate the molar mass of ethanol by summing the contributions of each element: \(\text{Molar mass} = (2 \times 12.01) + (6 \times 1.008) + (1 \times 16.00)\) g/mol.
4. Calculate the total mass of oxygen in one mole of ethanol, which is the atomic mass of oxygen times the number of oxygen atoms: \(\text{Mass of oxygen} = 1 \times 16.00\) g.
5. Calculate the mass percent of oxygen using the formula: \(\text{Mass \% of oxygen} = \left( \frac{\text{Mass of oxygen}}{\text{Molar mass of ethanol}} \right) \times 100\%\).