Hydroxide Ion is a diatomic anion whose chemical formula is OH⁻. This negatively charged ion is made up of a hydrogen and an oxygen atom which are bonded together by a covalent bond. Hydroxide is also known as a hydroxide radical. This is a diatomic compound with valency -1.

In this article, we will have a complete explanation of Hydroxide ions, and will also learn about their formation, structure, properties, uses, and more.

What is Hydroxide Ion?

Hydroxide Ion is a negatively charged molecule made up of a single hydrogen atom joined to one oxygen atom. The chemical formula of Hydroxide is OH⁻. It is formed due to a covalent bond between one oxygen atom and one hydrogen atom.

When a water molecule loses a hydrogen ion (H⁺), it can produce the conjugate base of water (H₂O). Hydroxide ions frequently participate in basic or alkaline reactions in aqueous solutions. A hydroxide ion and a hydrogen ion (proton) combine to make water:

OH^– + H⁺ → H₂O

Hydroxide + Hydrogen → Water

This process shows how a base (OH⁻) neutralizes an acid (H⁺). Strong bases like potassium hydroxide (KOH) and sodium hydroxide (NaOH) are examples of alkaline compounds that frequently include hydroxide ions.

In water, these materials separate to release hydroxide ions, increasing the pH of the solution. The amount of hydroxide ions present in a solution plays a major role in determining its pH. Bases are substances that enhance the concentration of hydroxide ions; alkaline or basic solutions have larger concentrations of hydroxide ions.

Water (H₂O) can autoionize (partially split) into hydroxide ions (OH⁻) and hydronium ions (H₃O⁺) in aqueous solutions. This process occurs in a tiny percentage of water molecules. The equation representing this equilibrium is given below:

Hydroxide Ion Lewis Structure

The chemical formula for hydrogen is OH⁻, making it a diatomic ion. It is made up of one hydrogen atom (H) and one oxygen atom (O) bound together covalently. The superscript -1 indicates that the oxygen atom is negatively charged, although the hydrogen atom is still positively charged. This particular combination of elements creates a diatomic ion, which is frequently present in a wide range of chemical compounds.

The following diagram illustrates the hydroxide ion’s molecular and Lewis structure:

The ion in this picture has an overall charge of -1 due to the existence of an additional electron, as indicated by the negative charge on oxygen and the line joining H and O, which symbolizes a single covalent link.

Hydroxide Ion Symbol

One oxygen atom along with one hydrogen atom combines to make hydroxide which is represented by the symbol OH^–.

Hydroxide Ion Examples

In chemistry, the hydroxide ion is very important, especially in acid-base processes. Few examples of commonly used hydroxide ions are given below:

Sodium Hydroxide

Caustic soda, also referred to as sodium hydroxide (NaOH), is a potent base that is employed in many different industries. Its uses in everything from soap making to chemical manufacturing demonstrate how important it is to a variety of processes.

Calcium Hydroxide

Slaked lime, also known as calcium hydroxide (Ca(OH)₃), is used in water treatment, agriculture, and building. It is a valuable compound because of its unique qualities, which include its capacity to neutralize acids.

Magnesium Hydroxide

The antacid properties of magnesium hydroxide (Mg(OH)₂) are well recognized. In medicine, it neutralizes excess stomach acid to relieve heartburn and indigestion.

Potassium Hydroxide

KOH, or potassium hydroxide, is a compound that finds use in various chemical and manufacturing processes. Its function in numerous industrial applications is facilitated by its alkaline nature.

Formation of Hydroxide

A chemical substance that contains the hydroxyl ion (OH^–) is referred to as an oxide. A base reacting with water or another acid usually forms hydroxides. As a negatively charged species, the hydroxyl ion forms hydroxide compounds when it combines with positively charged metals or other cations.

Here are two typical processes by which hydroxides might form:

Hydroxides of Metals

Metal hydroxides are created when metals react with water, particularly alkali and alkaline earth metals. For instance:

Metal (M) + Water (H₂O) → Metal Hydroxide (M(OH)₂) + Hydrogen (H₂O )

Depending on which metal is involved in the process, a certain hydroxide will produced.

Dissociation of Base

Substances known as bases have the ability to contribute electron pairs or take protons (H+). A base and water can react to produce hydroxide ions:

Base + Water → Hydroxide Ion + Conjugate Acid

To form hydroxide ions, for instance, ammonia (NH₃) can combine with water.

NH₃ + H₂O → NH₄⁺ + OH^–

Types of Hydroxide

Hydroxide are broadly classified in two types namely:

• Organic Hydroxide
• Inorganic Hydroxide

Organic Hydroxide

Compounds containing the hydroxyl group (-OH) joined to a carbon atom in an organic molecule are known as organic hydroxides. Organic hydroxides, which have a hydroxyl group covalently bound to a carbon atom, are frequently found in organic molecules such as carboxylic acids, phenols, and alcohols.

Methanol (CH₃OH), Phenol (C₆H₅OH) are few examples of organic hydroxide.

Inorganic Hydroxide

Compounds that do not belong to an organic molecule but yet include the hydroxide ion (OH⁻) are known as inorganic hydroxides. When a metal combines with water or an acid, it usually forms metal hydroxides. Because they are bases, inorganic hydroxides frequently dissociate in water to produce hydroxide ions.

Inorganic hydroxides include, sodium hydroxide (NaOH), Calcium Hydroxide (Ca(OH)₂), etc.

Also Check, Iron 3 Hydroxide

Hydroxide Ion Properties

Few of the important properties of hydroxide ion is described below:

Hydroxide Ion Formula

Hydroxide has Chemical Formula OH⁻.

Hydroxide Ion Valency

Hydroxide has a valency of -1. This indicates that the charge of hydroxide ions is -1.

Hydroxide Ion pH

Concentration of hydroxide ions determines the pH of hydroxide solutions. A solution that contains a lot of hydroxide ions will often be alkaline, meaning that its pH is greater than 7.

Hydroxides, in their organic and inorganic forms, display a variety of physical and chemical characteristics. In this section, we will examine the physical and chemical properties of hydroxides.

Physical Properties of Hydroxide

Some of the physical properties of the Hydroxide Ion are,

• State of Matter: Depending on the particular hydroxide component, hydroxides can exist in a variety of states, such as solids, liquids, or even gasses.

• Solubility: Hydroxides have varying degrees of solubility. While certain hydroxides may be insoluble or have limited solubility, others may be extremely soluble in water and create alkaline solutions.

• Color: Hydroxides come in a broad range of colors. While some could be colorless, others might have distinct hues that make them easy to identify.

• Melting and Boiling temperatures: Depending on the particular chemical, hydroxides have different melting and boiling temperatures. Typically, metal hydroxides tend to have higher melting points compared to non-metal hydroxides.

Chemical Properties of Hydroxide

Some of the chemical properties of hydroxide ions are,

• Acid-Base Reactions: Hydroxides take part in acid-base reactions because of their basic character. They easily combine with acids to create salt and water.

• Ionization: Hydroxides in aqueous solutions ionize to form hydroxide ions (OH^–), which add to the solution’s alkaline character.

• Redox reactions: Redox reactions, particularly those involving transition metals, can occur in some metal hydroxides. They could take part in oxidation-reduction processes.

• Dehydration: When exposed to heat, some hydroxides can go through dehydration processes in which they lose water molecules and become oxides.

Applications of Hydroxide

There are several uses for hydroxide-containing chemicals and hydroxide ions (OH⁻) in both daily life and diverse industries. Among the noteworthy applications are:

• Neutralization of acids: It is standard practice to neutralize acidic liquids with hydroxide ions. For instance, in industrial or laboratory settings, sodium hydroxide (NaOH) is frequently used to neutralize acids.
• Water Purification: Hydroxide compounds precipitate contaminants and regulate pH in water treatment. For this reason, water treatment facilities frequently utilize lime, also known as calcium hydroxide, or Ca(OH)₃.
• Production of Soap and Detergents: An essential component of the saponification process used to produce soap is sodium hydroxide, or NaOH. Additionally, it is employed in the production of different detergents.
• Textile Sector: The textile industry uses sodium hydroxide for fabric processing and treatment. It aids in removing impurities and prepare fibers for dyeing.

Read More,

• Potassium Hydroxide
• Magnesium Hydroxide
• Lithium Hydroxide

Hydroxide: Frequently Asked Questions

What is Hydroxide Ion Charge?

Hydroxide ion has a charge of -1, which is on the oxygen atom.

Is OH Hydroxide or Hydroxyl?

Hydroxide is a negatively charged ion made up of one oxygen atom and one hydrogen atom. Its chemical formula is OH. In contrast, the term “hydroxyl” describes the functional group -OH, which can exist in molecules. Thus, when OH is present as an ion, it is hydroxide.

Is Hydroxide an Acid?

No, Hydroxide is not an acid. Since they are the conjugate base of water (H₂O), oxide ions (OH^–) are frequently found in bases.

How are Hydroxides Formed?

Hydroxides are created by a variety of chemical processes, most frequently combining the hydroxide ion with a metal or another positively charged ion. The reaction of a metal with water is the most common technique for hydroxides formation.

What is Hydroxide Ion Used for?

Uses for hydroxide compounds are numerous. A few metal hydroxides are employed in the production of detergents and soaps. They also help treat water because some hydroxides have the ability to neutralize acidic materials.

What is Function of Hydroxide?

In chemical reactions, hydroxide ions can take up protons (H⁺) and function as bases. They play a crucial role in defining the basic nature of substances and contribute to the pH of solutions.

What is Chemical Formula of Hydroxide?

Hydroxide has the chemical formula OH^–

What is Atomic Mass of Hydroxide Ion?

Atomic Mass of Hydroxide Ion is 17 g/mol

Give the Reaction between Sodium Carbonate and Water.

When sodium carbonate (Na₂CO₃) and water (H₂O) react, sodium hydroxide (NaOH) and carbon dioxide (CO₂) are produced.​ Na₂​CO₃​ + H₂​O → 2NaOH + CO_2​