Final answer:
Impurities can affect the observed boiling point of a substance by increasing it compared to its pure form.
Step-by-step explanation:
Impurities can affect the observed boiling point of a substance. When impurities are present, the boiling point of a substance will increase compared to its pure form. This is because the impurities disrupt the regular arrangement of molecules or atoms in the substance, making it more difficult for the substance to transition from its liquid phase to its gaseous phase. As a result, more heat energy is required to reach the boiling point, leading to an increase in the observed boiling point.