enthalpy
2 synonyms for enthalpy, grouped by meaning and by how common each one is.
Noun — A measure of the total heat content of a system in thermodynamics, equal to its internal energy plus the product of its pressure and volume; changes in it show how much heat a process gives out or takes in at constant pressure.
Synonyms
Rare, literary or technical
Precise, but they will stand out — check the sense before using one.
heat content
H
How to use enthalpy
The word patterns that sound natural to a native speaker.
enthalpy change
standard enthalpy of formation
enthalpy of vaporisation
negative enthalpy
Technical; belongs to chemistry, physics and engineering.
Etymology
From Greek enthalpein "to warm in", from en- "in" and thalpein "to heat".
Full origin of enthalpy →Frequently asked questions
What is the difference between enthalpy and entropy?
Enthalpy measures heat content and tells you whether a process absorbs or releases energy. Entropy measures how spread out or disordered that energy is, and together with temperature it decides whether a reaction will actually happen.
What does a negative enthalpy change mean?
It means the system has released heat to its surroundings, so the reaction is exothermic and the products hold less energy than the reactants. A positive change means heat was absorbed and the reaction is endothermic.
Why is only the change in enthalpy measured?
Absolute enthalpy cannot be measured directly, but the difference between the start and end of a process can be, usually as heat exchanged at constant pressure. That is why textbooks always speak of delta H rather than H.
