How does a formula unit differs from molecular formula? Explain.

1 Answer
Nov 9, 2017

It is the expression of the minimum constituent atoms, but it is not the sum of the entire compound.


It is useful because it is one of the empirical measures that can be determined by experiment. However, it is NOT the representation of the actual molecule. It is usually called the "Empirical Formula" (from how it was determined) compared to the "Molecular Formula" (the actual number of each atom in a molecule).

For example, the "Empirical Formula" for benzene is CH, but the molecular formula is really #C_6H_6#.

In fact, the sequence of many organic compounds can be seen directly as a function of their empirical formulas.

Alkanes: #C_nH_(2n+2)#
Alkenes: #C_nH_(2n)#
Alkynes: #C_nH_n#