Question

What is the meaning of the two in ethyl alcohol, `C_2H_5OH`?

Answer 1

The subscript gives the number of atoms in the chemical formula.

Explanation:

Ethyl alcohol, `C_2H_5OH`, is a carbon chain of `2` carbon atoms, with an oxygen chemically bound to one end of the chain.

We could represent this is in the formulation:

`H_3C-CH_2-OH`

Carbon 1 (from the left) is bound to 3 hydrogens and to C2. C2 is bound to C1, 2 hydrogens and an oxygen atom. Because it is easier to write `C_2H_5OH` than the whole chain, it is a convenient representation.