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

This edge becomes an acceleration hotspot because pressure falls rapidly there while enthalpy density remains low.

From Science Daily ● Aug. 3, 2026

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

"But to predict new ceramic recipes with other transition metals, we had to address the enthalpy."

From Science Daily ● Jan. 3, 2024

Determine the enthalpy change per mole of zinc reacting for the reaction:

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

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

From Textbooks ● Feb. 14, 2019

Using these equations with the appropriate values for specific heat of ice, water, and steam, and enthalpies of fusion and vaporization, we have:

From Textbooks ● Feb. 14, 2019

Hess’s law can also be used to show the relationship between the enthalpies of the individual steps and the enthalpy of formation.

From Textbooks ● Feb. 14, 2019

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

We will often use values such as boiling or freezing points, or enthalpies of vaporization or fusion, as indicators of the relative strengths of IMFs of attraction present within different substances.

From Textbooks ● Feb. 14, 2019

Random Word

Spin the wheel and learn a new word!

---