What is mass% of Hydrogen in ethanol?

Question

Accepted Answer

To determine the mass percentage of hydrogen in ethanol (C₂H₅OH), we need to calculate the contribution of hydrogen to the total molecular mass of ethanol and express it as a percentage.

1. **Molecular Formula of Ethanol**: C₂H₅OH

2. **Atomic Masses**:
   - Carbon (C): 12.01 g/mol
   - Hydrogen (H): 1.01 g/mol
   - Oxygen (O): 16.00 g/mol

3. **Molecular Mass of Ethanol**:
   - Ethanol consists of 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom.
   - Total mass = (2 × 12.01) + (6 × 1.01) + (1 × 16.00)
   - Total mass = 24.02 + 6.06 + 16.00 = 46.08 g/mol

4. **Mass of Hydrogen in Ethanol**:
   - There are 6 hydrogen atoms in ethanol.
   - Total mass of hydrogen = 6 × 1.01 = 6.06 g/mol

5. **Mass Percentage of Hydrogen**:
   - Mass percentage = (Mass of hydrogen / Total molecular mass of ethanol) × 100
   - Mass percentage = (6.06 / 46.08) × 100 ≈ 13.13%

Therefore, the mass percentage of hydrogen in ethanol is approximately 13.13%, which corresponds to Option 2 (0.1313 when expressed as a decimal).

**Explanation for Other Options**:

- **Option 1 (0.52)**: This value is significantly lower than the calculated mass percentage of hydrogen in ethanol. It does not accurately reflect the contribution of hydrogen to the molecular mass of ethanol.

- **Option 3 (0.3413)**: This value is also incorrect as it overestimates the mass percentage of hydrogen. The calculation clearly shows that the correct percentage is approximately 13.13%.

- **Option 4 (0.4623)**: This option is incorrect as well, as it does not match the calculated mass percentage of hydrogen in ethanol. It is higher than the actual value.

In conclusion, the correct mass percentage of hydrogen in ethanol is 13.13%, which is represented by Option 2 (0.1313).