Final answer:
Carboxylic acids and phenols can be recovered from their chemically altered salt forms through methods like acidification or extraction.
Step-by-step explanation:
Carboxylic acids and phenols can be recovered from their chemically altered salt forms through various methods. One common method is acidification, where the salt is treated with a strong acid to convert it back into the free acid form. For example, if the salt is sodium carboxylate (RCOONa), it can be treated with hydrochloric acid (HCl) to form the carboxylic acid (RCOOH) and sodium chloride (NaCl) as a by-product:
RCOONa + HCl → RCOOH + NaCl
This reaction can be reversed by adding a strong base to the carboxylic acid to convert it back to the salt form. Another method is extraction, where the salt is dissolved in a suitable organic solvent and then treated with a strong acid or base to selectively extract the carboxylic acid or phenol. The extracted acid can then be recovered by evaporating the solvent or by further purification techniques, such as distillation or chromatography.