Question

Solubility of ethanol in water explain why ethanol (ch3ch2oh) is more soluble in water than is ethane (ch3ch3)

Answer 1

Ethanol is more soluble in water than ethane because it can form hydrogen bonds with water due to its hydroxyl (-OH) group. Ethane, with no such group, cannot form these hydrogen bonds, making it comparatively insoluble in water. The solubility of alcohols decreases as their carbon chain length increases.

Step-by-step explanation:

The solubility of ethanol (CH3CH2OH) in water can be explained by the presence of the hydroxyl group (-OH) in its structure, which allows ethanol to engage in hydrogen bonding with water. Unlike ethanol, ethane (CH3CH3) does not contain a hydroxyl group and therefore cannot form hydrogen bonds with water molecules, making it less soluble. The hydrogen bonds between water and ethanol are almost as strong as those within pure water or pure ethanol, which allows ethanol to dissolve readily in water.

As carbon chain length increases in alcohols, their solubility in water decreases because the nonpolar carbon chain does not interact favorably with water. This is why substances like 1-decanol, with long carbon chains, are generally insoluble in water. However, alcohols with four or fewer carbon atoms, like ethanol, are completely soluble in water due to their ability to form hydrogen bonds.

Answer 2

As the rule of thumb goes, "like dissolves like." Water is a polar solvent, ethanol is polar, whereas ethane is nonpolar. Ethanol molecules contain hydrogen atoms directly bonded to oxygen atoms and demonstrate a partial-positive charge, meaning that the hydrogen atoms are capable of forming hydrogen bondings- the strongest type of intermolecular interaction- without lone pairs on other atoms. In the case of dissolving ethanol in water, molecules of ethanol form hydrogen bonds with lone pairs on oxygen atoms in water molecules to release significant amounts of energy. On the other hand, ethene has no such structure that allow its molecules to establish hydrogen bonds and release little energy when hydrated with water molecules.

It takes energy to take molecules of the substance dissolved appart. The energy of hydration offsets this energy input in the case of ethanol but not ethene. The dissolving of ethanol is thus energetically favored at large amounts, whereas ethane-water mixtures tend to be most stable when in separation.