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Changes of state are examples of phase changes, or phase transitions. All phase changes are accompanied by changes in the energy of a system. Changes from a more-ordered state to a less-ordered state (such as a liquid to a gas) are endothermic.
States of Matter - PhET Interactive Simulations
Summary. Fusion, vaporization, and sublimation are endothermic processes, whereas freezing, condensation, and deposition are exothermic processes. Changes of state are examples of phase changes, or phase transitions. All phase changes are accompanied by changes in the energy of a system.
The temperature reflects the thermal energy content of the material—the addition of heat increase the vibrational motions, and temperature increases. Ultimately, the solid changes to a liquid and the liquid changes to a gas phase as more heat is added, as illustrated in Figure 1.9.1.
These changes are driven by two main factors: temperature and pressure. Temperature: When a substance is heated, its particles gain kinetic energy, which causes them to vibrate more vigorously and move further apart. If enough energy is absorbed, the particles can overcome the forces holding them together, leading to a phase change.
It is important to understand the difference between the energy associated with changes in temperature and changes in state where the temperature remains constant. This difference is most clearly depicted in a heating curve, which is a plot of the temperature versus heating time (or heat added).
Changes in temperature or physical state are caused by transfers of energy. Specific heat capacity determines the energy needed to change temperature, and specific latent heat is the energy...
