Endothermic

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This article is about the physical effect. For self-maintained thermal homeostasis, see Warm-blooded.

In thermodynamics, the word endothermic describes a process or reaction that absorbs energy in the form of heat. Its etymology stems from the Greek prefix endo-, meaning “inside” and the Greek suffix –thermic, meaning “to heat”. The opposite of an endothermic process is an exothermic process, one that releases energy in the form of heat.

The concept is frequently applied in physical sciences to e.g. chemical reactions, where chemical bond energy is converted to thermal energy (heat).

1 Overview
- 1.1 Endothermic processes
2 Implications for chemical reactions
3 Applications of endothermic processes
- 3.1 Endothermic materials in passive fire protection
4 See also
5 References
6 External links

[edit] Overview

Endothermic, also known as endergonic, refers to a transformation in which a system receives heat from the surroundings:

Q > 0

When the transformation occurs at constant pressure:

∆H > 0

and constant volume:

∆U > 0

If the surroundings do not supply heat (e.g., when the system is adiabatic), an endothermic transformation leads to an increase in the temperature of the system.^[1]

[edit] Endothermic processes

Some examples of endothermic processes are:^[2]

Cooking food
Melting of ice
Depressurising a pressure can

[edit] Implications for chemical reactions

Chemical endothermic reactions need heat to be performed. In a thermochemical reaction that is endothermic, the heat is placed on the reactants side (heat is necessary for and absorbed during the reaction).

[edit] Applications of endothermic processes

[edit] Endothermic materials in passive fire protection

Main article: Passive fire protection

Endothermic substances, both natural, e.g. gypsum, and synthetic, e.g. resin-based intumescents, are popular for use in heatshielding, ablation, materials in space physics, fireproofing, e.g. fire-resistive coatings for LPG vessels, and compartmentalisation of fire in buildings, which is the cornerstone of passive fire protection. Typically, the technological basis is the conversion of hydrates, or chemically bound water into vapour, or steam.