Oxides and Hydroxides

In hydroxides, a covalent bond links a hydrogen atom with an oxygen atom. The negative-charged hydroxide ion serves as a catalyst, nucleophile, ligand, base, etc. Hydroxide is also known as the hydroxyl radical, hydroxide ion, or hydroxyl ion.

An oxide is a chemical molecule that contains one or more oxygen atoms and another element. Most stable oxides, such as alumina (aluminium oxide), calcium oxide, and others, have oxygen in the -2 oxidation state.

Classification of oxides

Oxides are classified as basic, acidic, amphoteric or neutral, depending on their acid-base properties.

  • A basic oxide is an oxide that produces a base in water [alkaline and alkali metal oxides].
  • Acidic oxide is an oxide that forms an acid when it reacts with water [SO3, CO2, etc.].
  • An amphoteric substance can react chemically as an acid or a base [Al2O3, PbO, SnO, etc.].
  • Oxide can be neither acidic nor basic [CO, NO, NO2, etc.].

Characteristics of Hydroxide

In hydroxide, two electrons share oxygen bonds with hydrogen. Hydroxide has a negative charge because an electron has been absorbed.

  • Hydroxide – OH
  • Conjugate base – Oxide anion
  • Conjugate acid – Water
  • Monoisotopic mass – 17.003 g/mol
  • Molecular Weight – 17.007 g/mol

Important Hydroxide Compounds

The chemical formula of some important hydroxide compounds, and their applications, are given here.

Lithium hydroxide (LiOH)

In a test tube, lithium reacts with water to produce lithium hydroxide (LiOH) and hydrogen gas.

Chemical formula LiOH
Molecular weight 23.95 g/mol
Density 1.46 g/cm3
Melting & Boiling point 462 °C and 924°C

Applications of LiOH

Lithium hydroxide is used in a variety of applications.

  • Several lithium compounds, such as lithium chloride, lithium iodide, lithium bromide, and lithium fluoride, use lithium hydroxide (LiOH) as a starting material.
  • To absorb unwanted gas, LiOH is utilised.
  • The spacecraft’s scrubbers use lithium hydroxide to remove carbon dioxide from the air.

Aluminium hydroxide (Al(OH)3)

Aluminium hydroxide is a white, amorphous powder. It is soluble in alkaline and acidic solutions but not in water.

Chemical formula Al(OH)3
Molecular weight 78.00 g/mol
Density 2.42 g/dm3
Melting point 300 °C

Uses of Al(OH)3

Aluminium hydroxide has a variety of applications.

  • Aluminium hydroxide is used to treat heartburn, stomach pain, aching stomach and acid indigestion.
  • It’s also used to lower phosphate levels in people who have kidney disorders.

Magnesium hydroxide (Mg(OH)2)

Magnesium hydroxide is a chemical compound with low water solubility. It’s also known as magnesium (2+) hydroxide or Milk of Magnesia.

Chemical formula Mg(OH)2
Molecular weight 58.3197 g/mol
Density 2.3446 g/cm3
Melting point 350°C

Uses of Mg(OH)2

  • Magnesium hydroxide is a laxative that helps people with chronic constipation.
  • Magnesium hydroxide is an antacid used to treat indigestion, heartburn, and acid reflux.

Zinc hydroxide [Zn(OH)2]

Zinc hydroxide is an inorganic chemical with the formula Zn(OH)2. Zinc hydroxide reacts with both bases and acids. When exposed to strong acid, it dissolves as an insoluble hydroxide.

Chemical formula Zn(OH)2
Molecular weight 99.424 g/mol
Density 3.05 g/cm3
Melting point 125° C

Uses of zinc hydroxide

  • The zinc hydroxide is utilised as a retentive in careful dressings.
  • It’s utilised in the commercial production of pigments and pesticides as an intermediate.
  • The zinc component is applied to big bandages used to engross blood from wounds during medical treatments.

Sodium hydroxide (NaOH)

At room temperature, sodium hydroxide is a solid ionic chemical compound. Other names for caustic soda include Iye, soda lye, and sodium hydrate. It is produced as a byproduct of the chlorine production process. In its finest form, it is a colourless crystalline solid. Properties of sodium hydroxide are,

Chemical formula NaOH
Molecular weight 2.13 g/cm3
Density 39.997 g/mol
Melting and boiling point 318°C and 1,388°C

Uses of NaOH

  • Soaps and other detergents are made from sodium hydroxide.
  • By combining chlorine with sodium hydroxide, chlorine bleach is produced.