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Chemical Thermodynamics: Enthalpy definitions

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  • Enthalpy
    Amount of heat energy exchanged between a system and its surroundings at constant pressure, indicating energy changes in reactions.
  • Standard Enthalpy of Formation
    Heat change when one mole of a compound forms from its elements in their natural states under standard conditions.
  • Exothermic Process
    Type of reaction where heat is released, resulting in products with lower energy and stronger bonds than reactants.
  • Endothermic Process
    Type of reaction where heat is absorbed, leading to products with higher energy and weaker bonds than reactants.
  • Lattice Bond Energy
    Strength of connections between ions or molecules in a solid, influencing the energy required to break or form bonds.
  • Condensation
    Phase change from gas to liquid, typically associated with heat release and formation of stronger intermolecular attractions.
  • Freezing
    Phase change from liquid to solid, involving heat release and increased molecular order.
  • Deposition
    Direct transition from gas to solid, accompanied by heat release and formation of a structured solid.
  • Melting
    Phase change from solid to liquid, requiring heat absorption to overcome molecular attractions.
  • Vaporization
    Phase change from liquid to gas, involving absorption of heat to separate molecules.
  • Sublimation
    Direct transition from solid to gas, requiring significant heat absorption to break molecular bonds.
  • Energy Diagram
    Graphical representation showing energy levels of reactants and products, illustrating heat flow and reaction type.
  • Thermoneutral Reaction
    Process where reactants and products have equal energy, resulting in no net heat exchange.
  • System
    Part of the universe under study, such as the reactants and products in a chemical reaction.
  • Surroundings
    Everything outside the system that can exchange energy, such as the container or environment.