Chemistry 2005 JAMB Past Questions - Question 15: In the purification of impure samples of ethyl ethanoate synthesized by esterification, concentrated sodium trioxocarbonate (IV) solution is used to remove

Correct Answer

A

Explanation

In the purification of impure samples of ethyl ethanoate synthesized by esterification, concentrated sodium trioxocarbonate (IV) solution (commonly known as sodium carbonate or soda ash) is often used to remove acidic impurities.

During the esterification process, an ester is typically formed by the reaction between an alcohol (such as ethanol) and a carboxylic acid (such as ethanoic acid). However, the reaction may not go to completion, and there may be unreacted acid present in the mixture, along with other impurities.

Sodium carbonate is added to the impure mixture to neutralize any remaining acidic components. The reaction between sodium carbonate and acidic impurities involves the formation of carbon dioxide gas, water, and a salt. This reaction helps remove the acidic impurities from the mixture:

\[2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + CO_2 + H_2O\]

Here, \(CH_3COOH\) represents ethanoic acid, and \(Na_2CO_3\) is sodium carbonate.

The carbon dioxide gas produced escapes, leaving behind a purified solution of ethyl ethanoate and sodium ethanoate. After the sodium carbonate treatment, the mixture is usually separated, and the desired product (ethyl ethanoate) can be further purified through techniques such as distillation or washing.

It's important to note that the choice of purification methods may vary depending on the specific impurities present in the reaction mixture and the desired purity of the final product.