Question

As the carbon chain increases in aldehyde and ketone compounds, solubility in water:
A. Decreases
B. Increases
C. May increase
D. May decreases

Answer 1

Hint: Solubility is defined as the maximum amount of solute in grams that dissolved in a given amount of solvent at a particular temperature. The principle of solubility is often referred to as “like dissolve like”.

Complete step by step answer:
Since there exists H-bonding between the polar carbonyl group and the water molecules for the case of lower aldehydes and Ketones containing up to four carbon atoms hence the compounds such as methanal, ethanal, propanone, butanal are soluble in water. As we know there is an increase in the size of the alkyl group with increase in molecular mass, so there is a decrease in solubility with an increase in molecular mass. Due to this phenomenon, the molecules having a higher alkyl group are practically insoluble. Also due to the presence of larger hydrocarbon parts such as benzene rings, the aromatic halides and ketones have less solubility than their aliphatic analogues.

So, the correct answer is Option A.

Additional Information:
Acetone and Formaldehyde are the smallest ketone and aldehyde respectively. Also, acetone is an excellent solvent and used as paint thinner.

Note: All aldehydes and ketones are soluble in organic solvents that include toluene and n-hexane. The organic compounds that have a carbonyl functional group, $C=C$. The remaining two bonds for the carbon can be occupied by hydrogen or aryl groups. When either bond of the carbon bond on the carbon is occupied by hydrogen, then the compound is known as Aldehyde and if hydrogen does not occupy any bond then the group is known as Ketone. These compounds have both Human and plan origin such as camphor, lemongrass, and cortisone.