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Hydroxide Ion

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Identification
Molecular formula
OH-
CAS number
14280-30-9
IUPAC name
hydroxide
State
State

At room temperature, hydroxide usually exists as part of other compounds. As an ion itself, it does not exist as a pure substance in nature but is an essential component in many chemical reactions and solutions.

Melting point (Celsius)
318.00
Melting point (Kelvin)
591.15
Boiling point (Celsius)
100.00
Boiling point (Kelvin)
373.15
General information
Molecular weight
17.01g/mol
Molar mass
17.0070g/mol
Density
2.1300g/cm3
Appearence

Hydroxide in its solid form appears as a white powder. It is generally encountered as part of a compound, such as sodium hydroxide or calcium hydroxide, where it contributes to the overall physical properties of the compound.

Comment on solubility

Solubility of Hydroxide Ion (OH-)

The hydroxide ion (OH-) is a fundamental anion that plays a crucial role in various chemical processes. Its solubility is closely related to the solubility of the corresponding hydroxide compounds in aqueous solutions.

General Characteristics of Hydroxides

Hydroxides can be classified based on their solubility in water:

  • Soluble Hydroxides: Some metal hydroxides, particularly those of alkali metals (e.g., NaOH, KOH), and certain alkaline earth metals (e.g., Ca(OH)2 in moderation) are highly soluble in water.
  • Insoluble Hydroxides: Many transition and heavy metal hydroxides (e.g., Fe(OH)3, AgOH) are generally insoluble or only sparingly soluble, leading to distinct chemical behaviors in reactions.

The solubility of hydroxides often depends on:

  • Temperature: Generally, the solubility of many hydroxides increases with temperature.
  • pH Levels: The presence of strong acids can lead to the formation of water, thus shifting the equilibrium and affecting solubility.
  • Complex Ion Formation: Some ions can form soluble complexes, enhancing the solubility of certain hydroxides.

Summary

In summary, while OH- itself is infinitesimally small and exists freely in solution, the solubility of various hydroxide compounds varies widely. The properties and behavior of these hydroxides in solution are essential for understanding their applications in chemistry, biology, and environmental science. As the great chemist Antoine Lavoisier once said, “Nothing is lost, nothing is created, everything is transformed.” The transformations involving hydroxides are fundamental in many chemical reactions.

Interesting facts

Interesting Facts About Hydroxide Ion (OH-)

The hydroxide ion, represented as OH-, is a fundamental and widely studied anion in the field of chemistry. Its significance extends across various branches, making it an essential topic of discussion. Here are some intriguing facts about this versatile ion:

  • Acid-Base Chemistry: OH- plays a crucial role in acid-base reactions. It is a strong base and acts by accepting protons (H+) from acids, effectively neutralizing them.
  • Water's Dissociation: The formation of hydroxide ions occurs naturally in water via the dissociation of water molecules. This equilibrium is essential for maintaining pH levels in biological and chemical systems.
  • In Biological Systems: Hydroxide ions are involved in various biochemical processes. For example, they participate in enzyme-catalyzed reactions and influence cellular pH, which is critical for enzyme activity.
  • In Nature: Hydroxide ions are often found in various natural waters, influencing their pH and chemical composition. They contribute to the alkalinity of natural water sources.
  • Applications: Hydroxide ions are utilized in a myriad of industrial applications, including:
    • Pulp and paper production
    • Water treatment
    • Manufacturing of soaps and detergents
    • Food processing, especially in caramelization and blackening of foods

As noted by prominent chemists, "The hydroxide ion is a linchpin in the world of chemical reactions, linking acids and bases together." This quote encapsulates its essential role in maintaining balance in chemical equations and reactions. Its importance in both theoretical and practical chemistry makes it a compound worthy of in-depth study and appreciation.

In summary, the hydroxide ion's ability to influence pH, participate in chemical reactions, and its broad applications in everyday life underscore its significance in chemistry and beyond.

Synonyms
hydroxide
hydroxide ion
hydroxyl ion
Hydroxide anion
14280-30-9
oxidanide
Hydroxyl anion
Hydroxy ion
hydridooxygenate(1-)
14337-01-0
Hydroxy anion
Hydroxide(1-)
Hydroxide ion(1-)
OH-
UNII-9159UV381P
Hydroxyl ion (OH1-)
9159UV381P
OH
DTXSID8074281
CHEBI:16234
OH(-)
Oxygen, ion (O1-)
a hydroxyl group
Hydroxyl, ion
water ion(1-)
HYDROXY
water, ion(1-)
Oxygen ion (O1-)
Hydroxide (8CI,9CI)
DTXCID0034649
DTXSID301316295
DB14522
C01328
Q199877
Q27109967
HO-