Triethylamine, (CH3CH2)3N, is very slightly soluble in water but readily soluble (with stirring) in 1.5 M HCL.

Well, isn't triethylamine just a bit of a diva when it comes to solubility? It's like the water is telling it, "Sorry, buddy, we don't really vibe together." But then along comes 1.5 M HCL, and it's like a match made in a chemistry lab. They start stirring things up and suddenly triethylamine is all like, "Oh yeah, HCL, you get me!" It's a classic case of "opposites attract," I suppose. Chemistry can be quite the romantic comedy sometimes, don't you think?

Triethylamine, also known as (CH3CH2)3N, is a tertiary amine that consists of three ethyl groups attached to a nitrogen atom. It is a volatile liquid with a strong, fishy odor.

Now, let's address the solubility of triethylamine. It is considered to be slightly soluble in water. This means that it can dissolve to a small extent in water, but the amount that dissolves is relatively low. The solubility of triethylamine in water arises from the ability of water molecules to form hydrogen bonds with the nitrogen atom, as well as with the ethyl groups. However, its limited solubility is due to the nonpolar nature of the ethyl groups, which makes it difficult for triethylamine to mix well with the polar water molecules.

On the other hand, triethylamine readily dissolves in 1.5 M hydrochloric acid (HCl) with stirring. This is because hydrochloric acid is a strong acid and readily ionizes in water to produce hydrogen ions (H+) and chloride ions (Cl-). When triethylamine is added to hydrochloric acid solution, the nitrogen lone pair electrons on the amine can react with the hydrogen ions present in the solution, forming an ammonium ion (NH4+):

(CH3CH2)3N + HCl → (CH3CH2)3NH+ + Cl-

The formation of the ammonium ion makes triethylamine water-soluble because the ammonium ion can readily form hydrogen bonds with water molecules. This allows triethylamine to dissolve easily in hydrochloric acid solution, making it more soluble compared to its solubility in pure water.

In summary, triethylamine is slightly soluble in water due to the ability of water molecules to form hydrogen bonds with it. However, it readily dissolves in 1.5 M hydrochloric acid solution because of the formation of the water-soluble ammonium ion through a reaction with hydrogen ions present in the acidic solution.