Title: hydrate
Long Title: IUPAC Gold Book - hydrate
DOI: 10.1351/goldbook.15195
Status: current

Definition
Crystalline form of a compound in which water molecules are part of the crystal structure.

Notes
1) Association of water molecule(s) in a crystal can be of different strength.
2) The term "hydrate" may mean different things in different contexts. Common to all contexts is the content of water, which may be part of crystal structure or part of a molecule to which water has been added reversibly (e.g., chloral hydrate) or the elements of water incorporated covalently (e.g., carbohydrates).

Related Terms
- Crystalline: https://goldbook.iupac.org//terms/view/15166
- solvate: https://goldbook.iupac.org//terms/view/15234

Source
- PAC, 2009, 81, 971. 'Glossary of terms related to pharmaceutics (IUPAC Recommendations 2009)' on page 987 (https://doi.org/10.1351/PAC-REC-04-10-14)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/15195/html
- json: https://goldbook.iupac.org/terms/view/15195/json
- xml: https://goldbook.iupac.org/terms/view/15195/xml

Citation: Citation: 'hydrate' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.15195
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Accessed: 2026-04-17T19:58:46+00:00