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

---

Other Word Forms

Noun Inflected Forms

• enthalpies
  plural

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

See Examples For:

enthalpy enthalpies

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

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 high-entropy carbides all had a relatively uniform amount of enthalpy, so we could ignore part of the equation," Curtarolo said.

From Science Daily ● Jan. 3, 2024

Use this information to estimate the enthalpy of vaporization for ethanol.

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

Viewed in this manner, the enthalpy of sublimation for a substance may be estimated as the sum of its enthalpies of fusion and vaporization, as illustrated in Figure 10.28.

From Textbooks ● Feb. 14, 2019

Explain why the enthalpies of vaporization of the following substances increase in the order CH4 < NH3 < H2O, even though all three substances have approximately the same molar mass.

From Textbooks ● Feb. 14, 2019

Thus, in calculating enthalpies in this manner, it is important that we consider the bonding in all reactants and products.

From Textbooks ● Feb. 14, 2019

Which of the enthalpies of combustion in Table 5.2 the table are also standard enthalpies of formation?

From Textbooks ● Feb. 14, 2019

If we have values for the appropriate standard enthalpies of formation, we can determine the enthalpy change for any reaction, which we will practice in the next section on Hess’s law.

From Textbooks ● Feb. 14, 2019