"In thermodynamics, enthalpy is the sum of a thermodynamic system's internal energy and the product of its pressure and volume."
A measure of the heat content of a system. It can be used to calculate the heat transfer in a reaction at constant pressure, and is defined as H = U + PV.
Energy: The concept of energy and its different forms are essential for understanding Enthalpy.
Chemical reactions: The understanding of chemical reactions is crucial since Enthalpy is related to the energy changes that take place during these reactions.
State functions: Enthalpy is a state function, which means it only depends on the initial and final states of the system.
Enthalpy: The definition of Enthalpy, its types, and its significance are essential for studying Chemical Thermodynamics.
Enthalpy of reactions: The energy changes that occur during a chemical reaction can be expressed in terms of the Enthalpy of reactions.
Hess's law: Hess's law states that the Enthalpy change of a reaction is independent of the reaction pathway.
Enthalpy of formation: The Enthalpy of formation is the Enthalpy change when one mole of a substance is formed from its elements in their standard states.
Bond enthalpy: The bond Enthalpy is the energy required to break one mole of bonds in a compound.
Enthalpy of combustion: The Enthalpy of combustion is the Enthalpy change when one mole of a substance is burned completely in oxygen.
Enthalpy of solution: The Enthalpy of solution is the Enthalpy change when one mole of a solute is added to a solvent to form a solution.
Enthalpy of fusion: The Enthalpy of fusion is the Enthalpy change when one mole of a solid melts to form a liquid.
Enthalpy of vaporization: The Enthalpy of vaporization is the Enthalpy change when one mole of a liquid is converted into its vapor phase.
Enthalpy of mixing: The Enthalpy of mixing is the Enthalpy change when two or more substances are mixed to form a solution.
Enthalpy of reaction: The Enthalpy of reaction is the Enthalpy change that occurs during a chemical reaction.
Enthalpy diagram: The Enthalpy diagram is a graphical representation of the Enthalpy changes that occur during a chemical reaction.
Calorimetry: The experimental method used to measure Enthalpy changes is called calorimetry.
Standard Enthalpy of reactions: The Standard Enthalpy of reactions is the Enthalpy change when the reaction is carried out under standard conditions.
Enthalpy cycle: The Enthalpy cycle is a graphical representation of the Enthalpy changes for a set of related reactions.
Kirchhoff's law: Kirchhoff's law relates the Enthalpy changes at different temperatures.
Enthalpy and entropy: The relationship between Enthalpy and entropy is crucial for understanding the driving force of chemical reactions.
Enthalpy of Formation: The enthalpy change that occurs during the formation of one mole of a compound from its constituent elements in their standard states.
Enthalpy of Combustion: The enthalpy change that occurs when one mole of a substance is completely burned in an excess of oxygen.
Enthalpy of Reaction: The enthalpy change that occurs when a chemical reaction takes place at a constant pressure.
Enthalpy of Solution: The enthalpy change when a solute is dissolved in a solvent.
Enthalpy of Fusion: The enthalpy change that occurs when a solid is transformed into a liquid.
Enthalpy of Vaporization: The enthalpy change that occurs when a liquid is transformed into a gas.
Enthalpy of Neutralization: The enthalpy change that occurs when an acid reacts with a base to form water and a salt.
Enthalpy of Hydration: The enthalpy change when a solute is dissolved in water and the water molecules surround it, forming hydration shells.
Enthalpy of Formation of Ions: The enthalpy change when one mole of an ion is formed from one mole of its constituent atoms.
Enthalpy of Ionization: The enthalpy change that occurs when an electron is removed from an atom or an ion in the gas phase.
Enthalpy of Electron Affinity: The enthalpy change when an electron is added to a neutral atom in the gas phase.
Enthalpy of Atomization: The enthalpy change that occurs when one mole of an element in the gas phase is transformed into its constituent atoms.
Enthalpy of Sublimation: The enthalpy change that occurs when a solid directly transforms into a gas.
Enthalpy of Adsorption: The enthalpy change when a gas or a dissolved substance is adsorbed on the surface of a solid or liquid.
"It is a state function used in many measurements in chemical, biological, and physical systems at a constant pressure."
"The pressure–volume term expresses the work required to establish the system's physical dimensions, i.e. to make room for it by displacing its surroundings."
"The pressure-volume term is very small for solids and liquids at common conditions, and fairly small for gases. Therefore, enthalpy is a stand-in for energy in chemical systems."
"Yes, as a state function, enthalpy depends only on the final configuration of internal energy, pressure, and volume, not on the path taken to achieve it."
"The unit of measurement for enthalpy in the SI system is the joule."
"Other historical conventional units still in use include the calorie and the British thermal unit (BTU)."
"The total enthalpy of a system cannot be measured directly because the internal energy contains components that are unknown, not easily accessible, or are not of interest for the thermodynamic problem at hand."
"A change in enthalpy is the preferred expression for measurements at constant pressure, because it simplifies the description of energy transfer."
"The standard enthalpy of reaction is the enthalpy change when reactants in their standard states change to products in their standard states."
"The value can be measured by calorimetric methods even if the temperature does vary during the measurement, provided that the initial and final pressure and temperature correspond to the standard state."
"Enthalpies of chemical substances are usually listed for 1 bar (100 kPa) pressure as a standard state."
"Enthalpies and enthalpy changes for reactions vary as a function of temperature."
"Tables generally list the standard heats of formation of substances at 25 °C (298 K)."
"For endothermic processes, the change ΔH is a positive value; for exothermic processes, it is negative."
"The enthalpy of an ideal gas is independent of its pressure or volume."
"The enthalpy of an ideal gas depends only on its temperature, which correlates to its thermal energy."
"Real gases at common temperatures and pressures often closely approximate this behavior, which simplifies practical thermodynamic design and analysis."
"At constant pressure, the enthalpy change equals the energy exchanged with the environment by heat."
"Enthalpy is a stand-in for energy in chemical systems; bond, lattice, solvation, and other chemical 'energies' are actually enthalpy differences."