Molar mass of benzene is 78, What will be its imperial mass.

Question

Accepted Answer

The correct option is (2):

To determine the empirical mass from the molar mass, we first need to know the empirical formula of the compound. Benzene has the molecular formula C6H6. The empirical formula represents the simplest whole-number ratio of atoms in a compound. For benzene, the simplest ratio of carbon to hydrogen atoms is 1:1, meaning its empirical formula is CH. The empirical mass is then the sum of the atomic masses of the atoms in the empirical formula. 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 empirical mass of CH is 12 + 1 = 13 g/mol. We can also find the relationship between molar mass and empirical mass using the "n-factor," which is the ratio of the molar mass to the empirical mass. Here, n = Molar mass / Empirical mass = 78 g/mol / 13 g/mol = 6. This means the molecular formula (C6H6) is six times the empirical formula (CH).

The incorrect option is (1): 78. This value represents the molar mass of benzene, not its empirical mass. The molar mass is the mass of one mole of the substance, which for benzene (C6H6) is (6 * 12) + (6 * 1) = 72 + 6 = 78 g/mol.

The incorrect option is (3): 44. This value is not related to the empirical mass of benzene. For example, carbon dioxide (CO2) has a molar mass of approximately 44 g/mol (12 + 2*16 = 44), but it is not relevant to the empirical mass of benzene.

The incorrect option is (4): 56. This value is also not related to the empirical mass of benzene. For instance, the molar mass of nitrogen gas (N2) is 28 g/mol, and the molar mass of ethene (C2H4) is 28 g/mol. Neither of these is 56, and 56 does not correspond to a simple multiple or part of benzene's mass.