Question

Why are alcohols more soluble in water than alkanes of the same molecular weight?

Hint:

The solubility of alcohols in water is largely due to the ability of the hydroxyl group to form hydrogen bonds with water.

Answer 1

Step 1: Understanding the structure of alcohols and alkanes.
Alcohols (\( R-OH \)) contain a hydroxyl group (-OH), while alkanes (\( R-H \)) consist of only carbon and hydrogen atoms. The key factor in solubility is the ability of a molecule to form hydrogen bonds with water molecules.
Step 2: Hydrogen bonding in alcohols.
The hydroxyl group in alcohols is highly polar and can form hydrogen bonds with water molecules. These hydrogen bonds increase the solubility of alcohols in water, as water molecules can interact effectively with alcohol molecules.
Step 3: Lack of hydrogen bonding in alkanes.
Alkanes, on the other hand, are nonpolar and cannot form hydrogen bonds with water. As a result, alkanes are less soluble in water because they cannot interact effectively with water molecules.
Step 4: Conclusion.
Alcohols are more soluble in water than alkanes of the same molecular weight due to the ability of alcohols to form hydrogen bonds with water, which alkanes cannot do.
Final Answer: Alcohols are more soluble in water than alkanes because the hydroxyl group in alcohols forms hydrogen bonds with water molecules, increasing their solubility.
Final Answer: \[ \boxed{\text{Alcohols are more soluble in water due to hydrogen bonding between the hydroxyl group and water molecules.}} \]