Final answer:
Impurities in a substance increase its boiling point proportionally to the concentration of the solute and change other physical properties like the freezing point and solubility of gases.
Step-by-step explanation:
Impurities in a substance can have significant effects on its boiling point. When a solute is dissolved in a solvent, the vapour pressure of the solution decreases because the solute molecules occupy space at the surface of the liquid, which prevents some of the solvent molecules from entering the vapour phase. This phenomenon is known as boiling point elevation. The boiling point of a solution is thus higher than the boiling point of the pure solvent. Moreover, the increase in boiling point is proportional to the concentration of the solute, meaning that more impurities will result in a higher boiling point. The existence of impurities also alters the melting point, and solubility of gases, and can lead to the deposition of substances such as scale in teapots and industrial boilers. Therefore, high levels of purity are often required in certain industries, like electronics, where silicon must be extremely pure for semiconductor production. Impurities in these cases may be controlled to enhance desired properties. In summary, impurities change the physical properties of substances by altering vapour pressure, which in turn affects the boiling and freezing points of the material.