Latent Heat Transition
Latent Heat Transition - Related Videos
02:31
Phase Transitions
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2020
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to occupy...
02:44
Heating and Cooling Curves
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2020
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves. For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
02:39
Phase Transitions: Vaporization and Condensation
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2020
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...
02:33
Phase Transitions: Sublimation and Deposition
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2020
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
02:39
Phase Transitions: Melting and Freezing
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2020
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
FAQs
The supplied energy is associated with altering intermolecular interactions and reorganizing particle arrangement within the substance. Because this energy changes the system’s enthalpy rather than increasing the particles’ average kinetic energy, the temperature does not rise during the transition. This molecular interpretation connects observed phase changes with the energetic behavior of chemical substances.
Latent heat is associated with a change in phase and a corresponding change in enthalpy, while sensible heat is associated with a change in temperature. Heating and cooling curves help distinguish these contributions by showing temperature behavior alongside energy input or removal. This distinction is important when interpreting thermal changes in chemical systems.
Enthalpy provides a way to describe the energy absorbed or released as intermolecular interactions and particle arrangements change during a phase transition. The transition enthalpy therefore characterizes the thermal requirement of the change without treating the energy as an increase in average kinetic energy. Its measurement supports comparison and characterization of materials.
Phase diagrams organize the phase behavior of a substance under varying conditions and help identify where transitions between phases occur. When interpreted with transition enthalpy, they connect the location of a phase change with the energy absorbed or released during that change. This makes phase diagrams useful for predicting how substances respond as conditions vary.
Calorimetry provides a method for measuring the energy absorbed or released during a phase change, allowing the associated transition enthalpy to be determined. The resulting value supplies quantitative information about the substance’s thermal behavior. In chemistry, these measurements support material characterization and help relate observed phase changes to intermolecular interactions.
Heating and cooling curves show how temperature responds as energy enters or leaves a substance. Regions associated with phase transitions can be distinguished from regions where temperature changes, helping separate latent heat from sensible heat. Their interpretation provides evidence for when energy changes particle arrangement and enthalpy rather than average kinetic energy.
Latent heat measurements quantify the energy associated with a material’s phase transition, providing information about its thermal behavior and identity. That information supports material characterization and the evaluation of substances for thermal energy storage. It also contributes to predicting phase behavior, particularly when a system experiences varying conditions that influence its phase state.