Organic Chemistry MCAT Practice Exam

What happens to non-polar compounds in polar solvents?

1. They dissolve easily.

2. They form a stable solution.

3. They remain insoluble.

4. They react with the solvent.

The correct answer is: They remain insoluble.

Non-polar compounds tend to be insoluble in polar solvents due to the fundamental principle of "like dissolves like." This principle indicates that polar solvents, which have regions of partial positive and negative charge due to their molecular structure, interact favorably with other polar substances rather than with non-polar compounds. In a polar solvent, the solvent molecules engage in strong dipole-dipole interactions and hydrogen bonding, which are not compatible with the relatively weak van der Waals forces that dominate in non-polar substances. As a result, the non-polar molecules do not mix well with the polar solvent, leading them to remain separate and form distinct phases rather than creating a stable solution. This behavior highlights the immiscibility of polar and non-polar compounds in various chemical contexts, supporting the conclusion that non-polar compounds remain insoluble in polar solvents.