“Cyclohexylbenzene has the empirical formula C3H4′ Its molar mass is 160.3_ Its molecular formula Select one:”
The Correct Answer and Explanation is:
Cyclohexylbenzene’s empirical formula is C3H4, and its molar mass is 160.3 g/mol. The empirical formula represents the simplest whole-number ratio of atoms in a compound. In this case, C3H4 indicates that for every 3 carbon (C) atoms, there are 4 hydrogen (H) atoms in the simplest form of the molecule.
To determine the molecular formula from the empirical formula, we need to find the ratio of the molar mass of the compound to the molar mass of the empirical formula. First, we calculate the molar mass of the empirical formula:
- Carbon (C) has a molar mass of 12.01 g/mol, so for 3 carbon atoms: 3×12.01=36.03 g/mol3 \times 12.01 = 36.03 \, \text{g/mol}3×12.01=36.03g/mol
- Hydrogen (H) has a molar mass of 1.008 g/mol, so for 4 hydrogen atoms: 4×1.008=4.032 g/mol4 \times 1.008 = 4.032 \, \text{g/mol}4×1.008=4.032g/mol
- The total molar mass of the empirical formula (C3H4) is: 36.03 g/mol+4.032 g/mol=40.062 g/mol36.03 \, \text{g/mol} + 4.032 \, \text{g/mol} = 40.062 \, \text{g/mol}36.03g/mol+4.032g/mol=40.062g/mol
Next, we compare the molar mass of the empirical formula (40.062 g/mol) to the given molar mass of cyclohexylbenzene, which is 160.3 g/mol. To find how many empirical units fit into the molecular formula, divide the molecular molar mass by the empirical molar mass: 160.340.062≈4\frac{160.3}{40.062} \approx 440.062160.3≈4
This means the molecular formula is 4 times the empirical formula. Therefore, the molecular formula is: C3H4×4=C12H16C3H4 \times 4 = C12H16C3H4×4=C12H16
Thus, the molecular formula of cyclohexylbenzene is C12H16.
