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Potassium Oxide : Structure, Formula, Properties & Uses

Dec 29, 2022

Do you know sodium which is the most reactive metal? No? It is potassium! Potassium is like sodium, i.e., very reactive, soft, and vigorous. Due to its reactivity, it is kept in kerosene. Similar to sodium, potassium also reacts with oxygen and forms potassium oxide. But can you answer, is potassium oxide ionic or covalent? Is this compound acidic or basic? What are the applications of potassium oxide?

This section will let you solve all such queries about potassium oxide.



What Is Potassium Oxide?

It is a compound formed by the bonding between oxygen and potassium. It is also known as dipotassium oxide or potassium monoxide. It is an inorganic compound. Like sodium oxide, it is also a highly reactive and rarely encountered compound.


It is easy to guess whether it is ionic or covalent. Firstly, potassium is a metal, and metals are electropositive, while oxygen is one of the highly electronegative elements. So, polarisation occurs, and the compound formed is ionic.

Secondly, it is explained by the potassium oxide Lewis structure, which is explained further.


Structure and Formula of Potassium Oxide

The molecular formula of it is K₂O. In general terms, it is called alkali metal oxide. It is the simplest compound of potassium that is highly reactive.

This compound is an ionic compound. It is because potassium has only one electron in its outermost shell, and oxygen is short of two electrons to gain a fulfilled octet. Hence, two potassium atoms will donate their electrons to the oxygen atom and form ionic bonds. As a result, the compound form is also ionic.


The potassium oxide Lewis structure is given below:

Potassium oxide structure


The potassium ion has a +1 charge, while the oxygen ion has a -2 charge. For an electrically neutral compound, the charges must counterbalance each other. Therefore, two K-atoms are required to balance the -2 charge on the O-atom. As a result, the formula for it is K₂O.

Preparation of Potassium Oxide

Some methods for preparing it are


1. With the help of potassium peroxide:

  • The product obtained is potassium oxide on reacting potassium peroxide, i.e., K₂O₂, with potassium metal.

K₂O₂ + 2K → 2K₂O

  • On heating potassium peroxide at 500°C, it decomposes into pure potassium oxide and oxygen molecules.

2K₂O₂ → 2K₂O + O₂ ↑


2. With the help of potassium nitrate:

When potassium nitrate is treated with potassium metal, it gives potassium oxide with the release of nitrogen gas. This method is more favorable than the first one.

2KNO₃ + 10K → 6K₂O + N₂ ↑

3. With the help of potassium hydroxide:

Potassium hydroxide cannot be further dehydrated to the oxide. But it can react with molten potassium to produce potassium oxide and release hydrogen as a byproduct.

2KOH + 2K ⇌ 2K₂O + H₂ ↑

4. With the help of potassium metal:

When potassium metal reacts with oxygen, it gives potassium oxide. This reaction is represented as

4K + O₂ → 2K₂O

Physical Properties of Potassium Oxide

Potassium is a member of the sodium family, i.e., group I in the periodic table. It tends to complete its octet by releasing electrons. Therefore, it is highly reactive in its free form. When it is treated with oxygen, it readily makes a bond with the O-atom and forms potassium oxide. Some physical properties of potassium oxide are:

  • It is a pale yellow or white-colored crystalline and solid compound.
  • This molar mass is 94.2 g/mol.
  • It is widely used as a fertilizer.
  • It is denser than water. And the density of it is 2.35 gm/cm³.
  • It is an odorless compound.
  • It decomposes at 740°C.
  • It is soluble in ethanol and diethyl ether.
  • The heat capacity of this is 83.62 J/mol·K.
  • Its molecules of it form an antifluorite structure.

Chemical Properties of Potassium Oxide

The chemical properties of a compound are the properties that change the chemical composition of the compound. As potassium is a highly reactive metal, it is a reactive compound and can react vigorously.

  • Reacting this with excess water becomes strongly corrosive, and the compound forms potassium hydroxide.

K₂O + H₂O → KOH

  • It is a metal oxide, and generally, metal oxides are basic. Therefore, it is basic or alkaline and is very corrosive.
  • When it reacts with strong acids, it gives salt and water. This reaction shows that it is a basic compound.

K₂O + HCl → KCl + H₂O

K₂O + H₂SO₄ → K₂SO₄ + H₂O

K₂O + HNO₃ → 2KNO₃ + H₂O

These reactions are examples of neutralization reactions.

  • When heated above 300°C, it converts into potassium peroxide and potassium metal.

2K₂O → K₂O₂ + 2K

Uses and Applications of Potassium Oxide

It is highly vigorous and readily reacts with moisture. It is used for various purposes. Some of them are

  • In the agricultural industry, it is widely used as a fertilizer.
  • It is also used in glassmaking formulas and the cement-making industry.
  • It is insoluble in water and is a highly stable compound. This property makes it handy in the ceramic industry.
  • It is used by animal doctors in the treatment of animal-related diseases.
  • Generally, it is known as pure potash and is used in preparing glasses and soaps.
  • In the aerospace industry, it is used to manufacture structural compounds and lightweight bowls.
  • Like zygomycetes, etc., fungal infections, it is used to treat such infections.
  • In tiny amounts, it is also used in some medicines.

Safety Measures for Using Potassium Oxide

It is useful for various purposes, but its highly reactive nature makes it a dangerous chemical. So, it is necessary to take precautions while working with it. However, if you come into contact with potassium oxide somehow, you must take immediate first-aid measures. These are

1. If your eyes come into contact with potassium oxide:

  • Immediately rinse your eyes with a large amount of water for at least 30 minutes.
  • Wash your eyes by lifting your eyelids up and down.
  • While washing your eyes, if you have worn contact lenses, remove them.
  • Seek medical attention immediately.

2. If your skin comes in contact with potassium oxide:

  • Remove all the contaminated clothes as quickly as possible.
  • Immediately wash your contaminated area with a large amount of water.
  • Seek medical attention immediately.

3. If you have inhaled potassium oxide:

  • Remove the person who was exposed to potassium oxide from his place.
  • Start the first aid by giving him rescue breathing if his breathing has stopped.
  • If his heart has stopped working, give him CPR.
  • Transfer rapidly to the medical facility.


After going through the above article, you are now well informed about potassium oxide. It is an inorganic acid with a highly reactive characteristic property. The formula of potassium oxide is K₂O. It has a basic or alkaline nature. It gives neutralization reactions when treated with strong acids. Due to its different properties, it is used majorly as a fertiliser in agriculture. It is useful in the glass, ceramic, and optic industries. It becomes toxic when ingested and inhaled. Due to its toxic nature, it is necessary to take precautions while working with it.

Frequently Asked Questions

1. How many types of oxides does potassium form when exposed to air?

A. When potassium is exposed to air (i.e., oxygen), it forms three types of oxides. The oxide formation depends upon the availability of oxygen during the reaction.

  1. Potassium oxide, K₂O
  2. Potassium peroxide, K₂O₂
  3. Potassium superoxide, KO₂

The reaction takes place as

8K + 4O₂ → 2K₂O+ 2KO₂ + K₂O₂

2. What is potassium superoxide?

A. Potassium superoxide is an inorganic compound with the chemical formula KO₂. The oxidation state of oxygen in KO₂, potassium superoxide, is -1. It is a yellow-colored paramagnetic solid which decomposes in moist air. It has different chemical and physical properties than potassium oxide or potassium peroxide.

3. Does potassium oxide cause any health hazards?

A. It is an inorganic compound with the chemical formula K₂O. It is highly corrosive and vigorous in moisture and air. So, handling it with care and safety is needed during chemical reactions or while working with it. Some health hazards caused by potassium oxide are

  • If it comes in contact with the skin, it can cause skin irritation.
  • If it gets into your eyes, it can severely damage your eyes.
  • When inhaled, it can cause cough and shortness of breath.
  • On inhalation, it can irritate the nose, throat, and lungs.

So, it is necessary to wear gloves, lab coats, and safety glasses while working in the laboratory with this.

4. When potassium oxide is dissolved in water, what is the pH of the solution formed?

A. It is an ionic compound, and it has a basic nature. When dissolved in water, it completely breaks into K⁺ and OH⁻ ions. The concentration of [OH⁻] ions is used to calculate the pH of the solution.

pH = 14 – pOH

pH = 14 – 1.48 = 12.52

Hence, the pH of the solution formed will be 12.52.

Potassium Oxide


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