122.11 g/mol and an empirical formula of C2H5O2. Determine the molecular formula of a compound that has a molar mass of 122.11 g/mol and an empirical formula of C2H5O2. C2H5O2 C8H20O8 C6H15O6 C4H10O4 C3H7O3
The Correct Answer and Explanation is:
To determine the molecular formula from the empirical formula and molar mass, we need to follow a few steps.
Step 1: Calculate the molar mass of the empirical formula
The empirical formula given is C2H5O2. Let’s calculate its molar mass.
- Carbon (C): 12.01 g/mol × 2 = 24.02 g/mol
- Hydrogen (H): 1.008 g/mol × 5 = 5.04 g/mol
- Oxygen (O): 16.00 g/mol × 2 = 32.00 g/mol
So, the molar mass of the empirical formula (C2H5O2) is:
24.02 + 5.04 + 32.00 = 61.06 g/mol
Step 2: Compare the molar mass of the empirical formula with the given molar mass
The given molar mass is 122.11 g/mol.
Now, divide the given molar mass by the molar mass of the empirical formula:
122.11 g/mol ÷ 61.06 g/mol = 2
Step 3: Multiply the empirical formula by this factor
The factor we found is 2. This means the molecular formula contains 2 units of the empirical formula. So, we multiply each subscript in the empirical formula by 2:
- Carbon (C): 2 × 2 = 4
- Hydrogen (H): 2 × 5 = 10
- Oxygen (O): 2 × 2 = 4
Thus, the molecular formula is C4H10O4.
Step 4: Verify the molecular formula options
Looking at the given options:
- C2H5O2
- C8H20O8
- C6H15O6
- C4H10O4
- C3H7O3
The correct answer is C4H10O4.
Conclusion
The molecular formula of the compound is C4H10O4, which is derived by doubling the empirical formula (C2H5O2) to match the given molar mass of 122.11 g/mol.
