Identify mixture X / sodium salt: Mixture X consists of a carboxylic acid and a neutral compound which was separated by using 2M NaOH and filtered off through a buchner funnel / flask. the sodium...

Identify mixture X / sodium salt:

Mixture X consists of a carboxylic acid and a neutral compound which was separated by using 2M NaOH and filtered off through a buchner funnel / flask. the sodium salt was removed and dried in a dessicator.

The alkaline filtrate was then acidified with HCL, cooled in an ice bath and then filtered off through the buchner flask / funnel.

the identity of mixture X isn't part of this assignment, but I want to add it to my report anyway as it should gain extra marks.

The carboxylic acid was identified as benzoic acid via the melting point.

So

Mixture X + NaOH => Neutral sodium salt + ??OH??

??OH?? + HCL => Benzoic acid + H2O

 

Can you help me identify the missing compounds in this purification experiment?

 

Asked on by user6259290

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garthman99 | High School Teacher | (Level 2) Adjunct Educator

Posted on

There is not enough information to identify mixture X. Since they tell us that the carboxylic acid is benzoic acid then it could suggest that the other component in the mixture is a benzene derivative such as, benzene benzaldehyde or benzene itself as both are oxidized to give benzoic acid

Since they tell us that the other component in the mixture is a neutral compound we can rule out phenol since phenol is a weak acid: it is more acidic than aliphatic alcohols.

Benzaldehyde is one of the most useful organic compounds and benzoic acid is often viewed as an impurity in organic reactions. You have to use the color and odor of the mixture to make a reasonable inference if benzaldehyde was present since benzaldehyde is a colorless liquid with an almond like odor. It has a pKa of 14.90 though. So it is more likely that the neutral compound in mixture X is benzene

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