The mass precent of oxYgen in `109%` oleum is .

Options

A. `40%`
B. `63.18%`
C. `60%`
D. `24%`

Explanation

To find the mass percent of oxygen in 109% oleum, we can follow these steps:

### Step 1: Understand the Composition of Oleum
Oleum is a solution of sulfur trioxide (SO₃) in sulfuric acid (H₂SO₄). The term "109% oleum" indicates that there are 109 grams of H₂SO₄ in the solution.

### Step 2: Calculate the Moles of H₂SO₄
The molar mass of H₂SO₄ (sulfuric acid) is calculated as follows:
- H: 1 g/mol × 2 = 2 g/mol
- S: 32 g/mol × 1 = 32 g/mol
- O: 16 g/mol × 4 = 64 g/mol

Total molar mass of H₂SO₄ = 2 + 32 + 64 = 98 g/mol.

Now, calculate the moles of H₂SO₄ in 109 grams:
\[ \text{Moles of H₂SO₄} = \frac{109 \text{ g}}{98 \text{ g/mol}} \approx 1.112 \text{ moles} \]

### Step 3: Calculate the Moles of Oxygen Atoms
Each molecule of H₂SO₄ contains 4 oxygen atoms. Therefore, the total moles of oxygen atoms in the solution is:
\[ \text{Moles of Oxygen} = 4 \times \text{Moles of H₂SO₄} = 4 \times 1.112 \approx 4.448 \text{ moles} \]

### Step 4: Calculate the Mass of Oxygen
The mass of oxygen can be calculated using the molar mass of oxygen (16 g/mol):
\[ \text{Mass of Oxygen} = \text{Moles of Oxygen} \times \text{Molar Mass of Oxygen} = 4.448 \text{ moles} \times 16 \text{ g/mol} \approx 71.18 \text{ g} \]

### Step 5: Calculate the Mass Percent of Oxygen
The mass percent of oxygen in the oleum solution can be calculated using the formula:
\[ \text{Mass Percent of Oxygen} = \left( \frac{\text{Mass of Oxygen}}{\text{Total Mass of Solution}} \right) \times 100 \]
Substituting the values:
\[ \text{Mass Percent of Oxygen} = \left( \frac{71.18 \text{ g}}{109 \text{ g}} \right) \times 100 \approx 65.30\% \]

### Conclusion
The mass percent of oxygen in 109% oleum is approximately **65.30%**.

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