Question

A student is performing an acid-base extraction on unknown compounds, and she extracts the organic layer with 5% HCl solution and separates off the aqueous layer. She then adds sodium hydroxide solution to the aqueous layer and observes a white precipitate. Which of the following functional group(s) is most likely in the precipitated compound?

a. ether
b. amine
c. carboxylic acid
d. ester

Answer 1

The white precipitate formed when sodium hydroxide solution is added to the aqueous layer indicates the presence of a compound containing an -OH group. The compound is most likely a phenol, an organic compound with an -OH group attached directly to an aromatic ring.

Step-by-step explanation:

The white precipitate formed when the student adds sodium hydroxide solution to the aqueous layer indicates the presence of a compound containing an -OH group. Based on the given options, the compound is most likely a phenol. Phenols are organic compounds that have an -OH group attached directly to an aromatic ring. They react with aqueous sodium hydroxide to form salts.

Answer 2

amine

Step-by-step explanation:

We have to bear in mind that amines are basic compounds. This idea will be very important in attempting to answer this question.

So, when she adds 5% HCl solution in order to extract the organic layer, the amine forms a hydrochloride salt which is contained in the aqueous layer.

The addition of a base such as NaOH leads to the formation of a white precipitate of the amine.