How can I find out if the OH group of an alcohol makes a base of an alcohol, without indicators?

Answer

Hi Shalini,

I can immediately reassure you: an alcohol is not a base, despite the presence of an -OH group! By the way, did you know that sulfuric acid (hydrogen sulfate) also has two -OH groups? However, this is a strong acid and therefore certainly not a base!

How could you investigate that? Supposing for a moment that alcohol is a base, then the following reaction must occur in water:

CH₃-OH –> CH₃⁺ + OH^–

(I take methanol as an example for an alcohol). This reaction is analogous to the reaction of sodium hydroxide (NaOH) in water:

NaOH –> Na⁺ + OH^–

The presence of the OH^– -ion ​​can of course be demonstrated with an indicator. (In fact, that’s the easiest method). An alternative is to measure the electrical resistance of the aqueous solution. The presence of ions in a solution greatly reduces the electrical resistance.

(Note: Alcohols are actually very weak acids, so weak that there is virtually no ionization in aqueous medium.)