Question

What is responsible for the solubility of alcohol?

Answer 1

We need to know that the solubility of any compound is due to hydrogen bonding. Polar molecules occur when there is an electronegativity difference between the bonded atoms. Non polar molecules occur when electrons are shared equally between atoms of a diatomic molecule or when polar bonds in a larger molecule cancel each other out.

Complete answer:
We have to know that the $OH$ group in alcohol is responsible for polarity and solubility. Each alcohol consists of a carbon chain (always non polar) and $OH$ group (polar). If we talk of ethanol molecules, the chemical formula looks like this: ${C_2}{H_5}OH$ . So ethanol has a 2 carbon chain and $OH$ group. As water is polar, it attracts $OH$ groups. The carbon chain, on the other hand, is non polar so it gets repelled. The solubility of alcohols is therefore determined by the stronger of the two forces. Solubility of alcohol in water can be seen as since alcohols are soluble in water. This is due to the hydroxyl group in the alcohol, which is able to form hydrogen bonds with water molecules. Alcohols with a smaller hydrocarbon chain are very soluble. As the length of the hydrocarbon chain increases, the solubility in water decreases. With four carbon in the hydrocarbon chain and higher, the decrease in solubility becomes visible as the mixture forms two immiscible layers of liquid.

Note:
We have to remember that the alcohol is a functional group having $OH$ group( hydroxyl group). The solubility of alcohol depends upon hydrogen bonding. Hydrogen bonding has strong forces of attraction. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as $N$, $O$ or $F$ atom and another very electronegative atom.