Question

How many equivalent hydrogens does ethanol have?

Answer 1

Ethanol has three sets of equivalent hydrogens.

Explanation:

The structure of ethanol is

The molecule contains six `"H"` atoms. Some of them are different from each other.

For example, there are three equivalent `"H"` atoms on the `"CH"_3` group.

They are different from the hydrogens on the `"CH"_2` group.

And the `"H"` atom on the oxygen is different from all the others.

One way to check whether certain `"H"` atoms are equivalent is to replace each `"H"` atom with a group like `"Cl"` and see if you generate the same compound.

Replacing any `"H"` atom in the `"CH"_3` group gives `"ClCH"_2"CH"_2"OH"`.

Replacing any `"H"` atom in the `"CH"_2` group gives `"CH"_3"CHClOH"`.

Replacing the `"H"` atom on the `"O"` gives `"CH"_3"CH"_2"OCl"`.

Here is the NMR spectrum of ethanol.

(from en.wikipedia.org)

The three blue, the two green, and the single red hydrogen make up three different sets of equivalent hydrogens.