enthalpy

American  

[en-thal-pee, en-thal-] / ˈɛn θæl pi, ɛnˈθæl- /

noun

Thermodynamics.

enthalpies plural

1. a quantity associated with a thermodynamic system, expressed as the internal energy of a system plus the product of the pressure and volume of the system, having the property that during an isobaric process, the change in the quantity is equal to the heat transferred during the process. H

---

enthalpy British  

/ ˈɛnθəlpɪ, ɛnˈθæl- /

noun

1.  H.  Also called: heat content.   total heat.  a thermodynamic property of a system equal to the sum of its internal energy and the product of its pressure and volume

---

enthalpy Scientific  

/ ĕn′thăl′pē /

1. A partial measure of the internal energy of a system. Enthalpy cannot be directly measured, but changes in it can be. If an outside pressure on a system is held constant, a change in enthalpy entails a change in the system's internal energy, plus a change in the system's volume (meaning the system exchanges energy with the outside world). For example, in endothermic chemical reactions, the change in enthalpy is the amount of energy absorbed by the reaction; in exothermic reactions, it is the amount given off.

2. See also thermodynamics

---

Etymology

Origin of enthalpy

1925–30; < Greek enthálp ( ein ) to warm in ( en- en- ² + thálpein to warm) + -y ³

Compare meaning

How does enthalpy compare to similar and commonly confused words? Explore the most common comparisons:

• enthalpy vs. internal energy

Example Sentences

Current methods to assess the efficiency of hydrogen storage materials rely on dehydrogenation enthalpy and energy barriers, with the latter being particularly complex and computationally intensive to calculate.

From Science Daily • May 17, 2024

In simple terms, enthalpy is a measure of how sturdy each design is, and entropy a measure of the number of possible designs that all have similar strength.

From Science Daily • Jan. 3, 2024

To better understand the concepts of entropy and enthalpy in this application, think of a 10-year-old trying to construct a doghouse out of a giant pile of Legos.

From Science Daily • Jan. 3, 2024

The approach used to calculate for a reaction from values is the same as that demonstrated previously for enthalpy and entropy changes.

From Textbooks • Feb. 14, 2019

And I didn’t know that the enthalpy decrease in a converging passage could be transformed into jet kinetic energy if a divergent passage was added.

From "October Sky" by Homer Hickam