What is the mass percent of oxygen in H2O?

• A. 88.8%
• B. 50.0%
• C. 33.3%
• D. 11.2%

Answer: (A)

Verified step by step guidance

1. Identify the elements in the compound H2O and their respective quantities: 2 hydrogen atoms and 1 oxygen atom.
2. Find the atomic masses of hydrogen and oxygen from the periodic table: approximately 1.0 g/mol for hydrogen and 16.0 g/mol for oxygen.
3. Calculate the molar mass of H2O by summing the masses of all atoms: \(\text{Molar mass} = 2 \times 1.0 + 1 \times 16.0\) g/mol.
4. Calculate the mass percent of oxygen using the formula: \(\text{Mass \% of oxygen} = \left( \frac{\text{mass of oxygen}}{\text{molar mass of H2O}} \right) \times 100\%\).
5. Substitute the values into the formula and simplify to find the mass percent of oxygen in H2O.