Final answer:
When a liquid is heated, its temperature increases and it can undergo a phase change to become a gas. When a liquid is cooled, it can undergo a phase change to become a solid.
Step-by-step explanation:
When a liquid is heated, it undergoes changes in temperature and phase. As the temperature of a liquid increases, its particles gain more energy and move more rapidly, resulting in an increase in temperature. At a certain temperature, called the boiling point, the liquid undergoes a phase change and turns into a gas. On the other hand, when a liquid is cooled, it can undergo a phase change and turn into a solid, a process called freezing.
provides the energy needed to overcome the intermolecular forces holding the particles together. The heating curve illustrates this phase change as a horizontal line on a temperature vs. heat added graph, indicating a constant temperature during the transition. According to LibreTexts<\/em>, the enthalpy of fusion is the energy required for the solid to liquid transition.
Substances such as water show a distinct heating curve. For ice, heat is absorbed at a constant rate until it reaches 0°C, where it remains constant as the phase change to liquid water occurs. Post melting, the temperature of the liquid water increases until it reaches its boiling point. The phase change from solid to liquid and then to gas involves the enthalpies of fusion and vaporization. However, supercooling or superheating may cause deviations in this behavior.