The solubility of carbon tetrachloride (CCl₄) in water at 25 °C is 1.2 g/L. The solubility of chloroform (CHCl₃) at the same temperature is 10.1 g/L. Why is chloroform almost ten times more soluble in water than carbon tetrachloride?

Key Concepts

Polarity

Polarity refers to the distribution of electrical charge over the atoms in a molecule. Polar molecules, like water, have a significant difference in electronegativity between their atoms, leading to partial positive and negative charges. In contrast, carbon tetrachloride (CCl4) is a nonpolar molecule due to its symmetrical tetrahedral shape, which prevents any dipole moment. This difference in polarity affects solubility, as polar solvents dissolve polar solutes more effectively.

Hydrogen Bonding

Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine. Chloroform (CHCl3) can engage in hydrogen bonding with water due to its polar C-H and C-Cl bonds, allowing it to mix more readily with water. In contrast, carbon tetrachloride lacks the ability to form hydrogen bonds, resulting in its lower solubility in water.

Like Dissolves Like

The principle of 'like dissolves like' states that polar solvents tend to dissolve polar solutes, while nonpolar solvents dissolve nonpolar solutes. Since water is a polar solvent, it is more effective at dissolving polar substances. Chloroform, being more polar than carbon tetrachloride, aligns better with water's polarity, leading to its higher solubility. This concept is fundamental in predicting solubility behaviors in various chemical systems.