How many moles of oxygen gas are present in a balloon containing 20.0 grams of pure oxygen gas (O_2)?

• A. 2.50 mol
• B. 0.625 mol
• C. 1.25 mol
• D. 0.313 mol

Answer: (B)

Verified step by step guidance

1. Identify the given information: the mass of oxygen gas (O\_2) is 20.0 grams.
2. Determine the molar mass of oxygen gas (O\_2). Since each oxygen atom has an atomic mass of approximately 16.00 g/mol, the molar mass of O\_2 is calculated as \$16.00 \times 2 = 32.00$ g/mol.
3. Use the formula to convert mass to moles: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\).
4. Substitute the known values into the formula: \(\text{moles of O\_2} = \frac{20.0 \text{ g}}{32.00 \text{ g/mol}}\).
5. Perform the division to find the number of moles of oxygen gas present in the balloon.