Question

In general, the solubility of a short chain carboxylic acid is greater than an ester with the same number of carbons. For example, butyric acid (four carbon atoms) is infinitely soluble in water, whereas ethyl acetate is only partially soluble in water (8 g/100 mL).

Select the statement that correctly explains why the water solubility of the carboxylic acid is greater than that of the ester.

a. Ethyl acetate has two -CH3 groups while butyric acid has only one.
b. The carboxylic acid is much more soluble because the-COOH group is on the end of the molecule and is therefore more accessible to H2O.
c. An ester group (-COO-) cannot form hydrogen bonds with water since there are no hydrogen atoms in the ester group.
d. Carboxylic acid groups (-COOH) can form hydrogen bonds with each other, but ester groups (Coo-) cannot.
e. A carboxylic ad roup CH) can form more hydrogen bonds with water than an ester group (-COO-).

Answer 1

A carboxylic acid group (-COOH) can form more hydrogen bonds with water than an ester group (-COO-).

Step-by-step explanation:

The carboxylic acid group (-COOH) is found in the carboxylic acids. This group is ultimately responsible for the solubility of carboxylic acids in water. It is worthy of note that the high boiling points of low molecular weight carboxylic acids is often because they are capable of intermolecular hydrogen bonding which leads to the dimerization of carboxylic acid.

The solubility of carboxylic acids decreases as the length of the alkyl chain increases. Hence, a long chain carboxylic acid is less soluble in water than shorter chain carboxylic acids.

Ester molecules can't form hydrogen bonds with each other but they do form weak hydrogen bonds with water. This leads to the solubility of low molecular weight esters. However, if a carboxylic acid and an ester posses the same length of alky chain, the carboxylic acid will form more hydrogen bonds and thus be more soluble in water than than a corresponding ester of the same chain length.