Understanding Molecular Formula and Mass from an Empirical Formula: The Case of CH

Chemistry often involves determining the molecular formula and mass from an empirical formula. The problem at hand is an interesting case where the empirical formula is CH, and it is given that the mass of the compound is 1/6 of its molecular mass. Let's break down the process and reveal the molecular structure.

The Process of Determining Molecular Formula and Mass

When the empirical formula is given as CH, it signifies a compound having one carbon (C) and one hydrogen (H) atom for every atom in the empirical formula. The empirical formula mass (EFM) of CH is calculated by adding the atomic masses of carbon and hydrogen. The atomic mass of carbon (C) is approximately 12 g/mol, and the atomic mass of hydrogen (H) is approximately 1 g/mol. Therefore, the EFM of CH is:

EFM of CH 12 g/mol 1 g/mol 13 g/mol

Given that the empirical formula mass is 1/6 of the molecular mass (MM), we can set up the following equation to find the molecular mass:

1/6 * MM 13 g/mol

Solving for MM, we get:

MM 13 g/mol * 6 78 g/mol

Identifying the Molecular Formula and Compound

Since the empirical formula and the molecular mass are known, we can determine the molecular formula. The molecular formula (MF) is six times the empirical formula, meaning we multiply the number of carbons and hydrogens in the empirical formula by 6. Hence, the molecular formula is:

MF C6H6

The molecular mass of C6H6 (benzene) is:

MM 6 * 12 g/mol 6 * 1 g/mol 72 g/mol 6 g/mol 78 g/mol

This confirms our calculation. However, we need to determine the specific compound. Given the structure and the properties, the molecule with a hexagonal ring and six carbons and one hydrogen per carbon fits the description of an aromatic compound. Benzene (C6H6) is a well-known aromatic compound with the molecular mass of 78 g/mol, matching our calculated value.

Conclusion

In conclusion, when the empirical formula is CH and the empirical formula mass is 1/6 of the molecular mass, the molecular formula is C6H6, and the molecular mass is 78 g/mol. This compound is likely benzene, a well-known aromatic hydrocarbon. Understanding how to derive the molecular formula and mass from the empirical formula is crucial in chemical analysis and can be applied to a wide range of chemical compounds.

Keywords: empirical formula, molecular formula, molecular mass, benzene