The molar mass of benzene, an important industrial solvent, is 78.0 g/mol and its empirical formula is CH. What is the molecular formula for benzene?
gormula mass for CH is 13. Divide 78 by 13, and get 6. So the mol formala must be C6H6
To find the molecular formula for benzene, we need to determine the ratio between the empirical formula mass and the molar mass.
The empirical formula of benzene is CH, which has a mass of 12.01 g/mol for carbon (C) and 1.01 g/mol for hydrogen (H). Therefore, the empirical formula mass is:
(12.01 g/mol) + (1.01 g/mol) = 13.02 g/mol
The molar mass of benzene is given as 78.0 g/mol.
To find the ratio, we divide the molar mass by the empirical formula mass:
78.0 g/mol / 13.02 g/mol = 5.98
The ratio is approximately 6.
This means that the molecular formula of benzene is 6 times the empirical formula.
Therefore, the molecular formula for benzene is C6H6.
To determine the molecular formula for benzene based on its empirical formula and molar mass, we need to find the ratio between the empirical formula weight and the molar mass and then multiply the subscripts of the empirical formula by this ratio. Here's how you can do it:
1. Find the empirical formula weight:
- The empirical formula of benzene is CH, which consists of one carbon atom (atomic mass = 12.01 g/mol) and one hydrogen atom (atomic mass = 1.01 g/mol).
- Add the atomic masses: (1 × 12.01 g/mol) + (1 × 1.01 g/mol) = 13.02 g/mol.
2. Find the ratio between the empirical formula weight and the molar mass:
- Divide the molar mass of benzene by the empirical formula weight: 78.0 g/mol ÷ 13.02 g/mol = 5.98.
- Round this ratio to the nearest whole number (in this case, 6).
3. Multiply the subscripts of the empirical formula by the ratio obtained:
- The empirical formula CH will become C6H6, as both the carbon and hydrogen subscripts are multiplied by 6.
Therefore, the molecular formula for benzene is C6H6.