What happens to sugar molecules \(\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)\) when they are dissolved in water?

Solubility is a fundamental concept in chemistry that describes a substance's ability to dissolve in a solvent. It is essentially how well a solute (such as sugar) can be dissolved by a solvent (like water) to form a homogeneous mixture known as a solution. The extent to which a solute dissolves in a solvent depends on factors such as temperature, pressure, and the nature of the solute and solvent.

Dissolution involves the breaking and making of bonds; when sugar dissolves in water, the bonds between the sugar molecules are broken, and new interactions between the sugar and water molecules are formed. The sugar molecules become thoroughly mixed with the water molecules to the point where they will not easily separate into two distinct phases. Understanding this process is critical in various fields such as cooking, pharmaceuticals, and environmental science, as it impacts how substances interact and behave in countless situations.

Molecules can be classified as polar or nonpolar, and this distinction is crucial for predicting solubility. Polar molecules, like water (H_2O), have an uneven distribution of electrical charge, leading to the formation of positive and negative poles. These molecules have dipole-dipole interactions and can attract other polar molecules, as well as ions.

Nonpolar molecules, in contrast, have an even distribution of electrical charge and do not have distinct poles. They are typically not soluble in polar solvents like water but dissolve well in nonpolar solvents. Sugar (C_{12}H_{22}O_{11}) is a polar molecule because of its multiple hydroxyl (OH) groups that can form hydrogen bonds with water. This explains why sugar dissolves in water: the attractive forces between the water molecules and sugar molecules overcome the intermolecular forces holding the sugar molecules together.

When sugar dissolves in water, a physical change occurs. A physical change is when a substance alters its physical properties without changing its chemical structure. Physical changes are generally reversible, and the original substance can often be retrieved through physical means such as evaporation or filtration.

In the case of sugar in water, though we cannot see the sugar anymore, it remains chemically the same, simply dispersed at the molecular level through the water. This process is different from a chemical change, where substances react to form new substances with different chemical structures. For example, burning sugar would result in a chemical change as it produces new substances like carbon dioxide and water. Thus, understanding physical changes helps us recognize how substances can be utilized differently without being altered fundamentally on a molecular level.