Sub-topic #2: Types of Water

• What is essential water in the context of hydrated compounds?


  It forms an integral part of the molecular or crystalline structure of a compound.
• How is nonessential water retained by solids?


  It is retained due to physical forces and is not integral to the crystal structure.
• What is water of constitution?


  It is water that is chemically combined within a compound’s molecular structure.
• What is water of crystallization also known as?


  It is also known as water of hydration.
• How is water of crystallization related to the structure of a compound?


  It is stoichiometrically bound into a crystal and is a definite part of the structure.
• What are hydrates?


  They are crystal salts containing water of hydration.
• What is occluded water?


  It is physically trapped inside the pores or voids of a substance.
• How can occluded water be released?


  It can be released by physical processes, such as drying.
• What is adsorbed water?


  It is water molecules that adhere to the surface of a substance due to physical forces.
• How is sorbed water defined?


  It is a general term that includes both adsorbed and absorbed water.
• Essential Water

  • Water that is chemically bound within the crystal structure of a compound and necessary for its stability.
• Essential Water

  • It is usually lost only when the compound is significantly heated or decomposed.
• Nonessential water

  • Retained by the solid as a consequence of physical forces.
• Nonessential water

  • Water that is not integral to the crystal structure of a substance but may be present due to absorption or hydration.
• Nonessential water

  • It can typically be removed by drying or mild heating without affecting the structure of the compound.
• Water of Constitution

  • Water that is chemically combined within a compound’s molecular structure, often released only when the compound undergoes decomposition or significant chemical change.
• Water of Crystallization

  • Also known as water of hydration
  • Water that is stoichiometrically bound into a crystal.
• Water of Crystallization

  • Water is a definite part of the structure of the
  • compound.
  • While the water is found within a crystal, it is not directly bonded to a metal cation.
• Occluded Water

  • It is not chemically bound and can be released by physical processes, such as drying or mechanical manipulation.
• Adsorbed Water

  • Water molecules that adhere to the surface of a substance due to physical forces (van der Waals forces or hydrogen bonding).
• Adsorbed Water

  • This water is relatively weakly bound and can be removed by drying or mild heating.
• Sorbed Water

  • It is taken up into the interior of a material, while adsorbed water sticks to its surface.
• Sorbed - refers to water held by a substance through either or both mechanisms.