Barium Hydroxide


Barium Hydroxide is a white granular compound. It is made up of Barium oxide and water. It is mainly used to produce other Barium products.

Barium hydroxide has the chemical formula Ba(OH)₂ₓ. One of the principal compounds of the element barium is its monohydrate, which is alternatively known as baryta or baryta-water. However, in the commercial field, the white granular monohydrate of barium is used for many applications. 

Chemical Structure of Barium Hydroxide

The chemical formula of Barium Oxide is Ba(OH)₂. The chemical formula of Barium Hydroxide is interesting. As you can see from the name, Barium Hydroxide is made up of Barium and Hydroxide. So, logically speaking, the formula should be Ba(OH). Then why do we write Ba(OH)₂ as the formula of Barium Hydroxide? This is because Barium has two positive ions while hydroxide has one negative one. So in order to show Barium as a neutral compound, we add another hydroxide to Barium Hydroxide and make it neutral

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Properties of Barium Hydroxide

Molar Mass

In order to find the molar mass of Barium Hydroxide, we need to add the molar masses of the elements that build this compound. The molar mass or molecular weight of Barium is 137.33. There is only one Barium in the compound. The molar mass of hydrogen is 1.008. There are two hydrogens in the compound. So the total molar mass of the two hydrogens combined is 2.016. The molar mass of oxygen is 15.999. There are two oxygens and hence the total molar mass of the two oxygens combined is 31.998. Now if we add these numbers we get 171.344. So the molar mass of Barium Hydroxide is 171.344g/mol.

Barium Oxide: A Strong Base

A base is that chemical species that reacts with water to give out hydroxide ions. A strong base is that base that can get completely dissociated in H2O to give out the exact number of anions and cations that the elements in the unbroken base had.

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Melting Point

The melting point of Barium Hydroxide differs with the amount of water in it. The octahydrate form of Barium oxide melts at 78-degree celsius. The monohydrate form melts at 300-degree Celsius and the anhydrous form melts at 407-degree celsius.


Although Barium Hydroxide is soluble in water, it is only slightly soluble. You need a Barium Hydroxide compound with a Molar Concentration of 0.1 M if you want it to dissolve in water.

Boiling Point

Barium Hydroxide boils at 780-degree celsius. If you keep on boiling and the temperature reaches 800-degree celsius, it will decompose and give out Barium Oxide.

Other Properties of Barium Hydroxide 

  • Barium hydroxide is white in colour.

  • It generally appears as granular solid.

  • It is odourless.

  • The pH of Barium Hydroxide is 11.27

  • The density of the monohydrate form of Barium Hydroxide is 3.74 g/cubic cm. And the density of the octahydrate form is 2.18 g/cubic cm.

Properties of Barium Hydroxide At A Glance

Physical Appearance

White, Odourless and Granular

Chemical formula


Molar mass

171.344 g/mol

pH of Barium Hydroxide



3.74 g/cubic cm when it comes to the monohydrate form. 2.18 g/cubic cm when it comes to the octahydrate form.


It is slightly soluble in water ( Upto 0.1 M of molar concentration)

Melting point

78 degree C ( For the octahydrate form), 300-degree C (for the monohydrate form), 407 degree C ( for the anhydrous form)

Boiling Point of Barium Hydroxide

780 degree C

Endothermic Reaction

The article on Barium Hydroxide will remain incomplete if we don’t talk about endothermic reaction and the role of Barium Hydroxide in it. Endothermic reaction is any reaction that borrows heat from the surrounding areas. The area thus becomes noticeably cool.

You can see this endothermic reaction if you mix Barium hydroxide with ammonium chloride. As you mix the two compounds in a beaker the temperature shoots down rather too quickly. If you measure the temperature inside the beaker, you will see that it has gone down below -20 degrees. The reaction absorbs the surrounding heat and results in the production of ammonia, barium chloride and water.


Barium hydroxide is primarily used to produce other barium products. How these products are used is discussed later on. Barium hydroxide is also used in laboratories to measure the concentration of weak acids. This process is called titration. This compound is also used to make glass, grease or other alkalis. It is also used in the treatment of sewage water. 

Here’s a Recap

  • Barium hydroxide is a white, granular compound.

  • It is made of Barium and Hydroxide ions.

  • In its original form, it is ionic in nature.

  • Barium hydroxide has a molecular weight of 171.344 g/mol.

  • Barium hydroxide is a strong base as it dissociates itself completely in water and gives out BaO cation and Hydroxide cation.

  • It takes 78-degree Celsius for the octahydrate form of barium hydroxide to melt. It takes 300 degrees and 407-degree Celsius for the monohydrate and the anhydrous forms to melt.

  • The boiling point of Barium hydroxide is 780-degree Celsius. If you heat the compound further, it will result in thermal decomposition and you will get Barium Oxide.

  • Barium Hydroxide can get dissolved in water, it is only slightly soluble. Barium Hydroxide compound with a Molar Concentration of 0.1 M will dissolve in water. The compound with higher molar concentration cannot dissolve in water.

Barium Hydroxide Can Be Hazardous

Although barium hydroxide is not as dangerous as, say, acids, it is a corrosive material. It can harm your skin, eyes, fingers etc. There is evidence of Kidney damage too because of the prolonged exposure to barium hydroxide. Inhalation of barium oxide can harm the respiratory tract. Hence, in the industrial setting, barium hydroxide is handled carefully by trained workers. 

Barium hydroxide is too dear for the teachers to show you how the endothermic reaction moves forward. The compound is not used in the domestic setting. Yet, you must read about the compound because of its unique properties and because of its applications in the industrial areas.

FAQ (Frequently Asked Questions)

1. What is Barium Hydroxide?

Ans. Barium hydroxide is a white, granular solid compound. Its chemical formula is Ba(OH)₂.

2. What is Barium Hydroxide Made of?

Ans. Barium hydroxide is made up of Barium cation and hydroxide cation. However, it is produced with the help of Barium oxide and water.

3. How is Barium Hydroxide Prepared?

Ans. Generally, barium hydroxide is prepared by dissolving barium oxide in water. The reaction results in the formation of the octahydrate form of barium hydroxide. This octahydrate form of barium oxide can be heated to turn it into monohydrate barium hydroxide.

4. Is Barium Hydroxide Ionic?

Ans. In its original form, barium hydroxide is ionic. It is made up of Ba2+ cation and OH- cation. Hence there is no way that the compound can get neutralised in the form. In order to make the compound neutral, the number of OH is increased to 2.

5. What are the Main Properties of Barium Hydroxide?

Ans. The main properties of barium hydroxide are 

  • It is white in colour.

  • It is a granular solid compound.

  • The density of the monohydrate form of barium hydroxide is 3.74 g/cubic cm. The density of the octahydrate form is 2.18 g/cubic cm.

  • Its molar mass is 171.344 g/mol.

  • Its melting point is 78 degrees C ( if it is the octahydrate form), 300 degrees C (if it is monohydrate form), 407 degrees C ( if it is the anhydrous form).

  • Its boiling point is 780 degree C.

  • The pH of Barium hydroxide is 11.27.

  • It is slightly soluble in water. You can dissolve only 0.1 M of barium hydroxide concentration in water.

6. What is an Endothermic Reaction?

Ans. The reaction where the compounds draw heat from the surrounding areas to react is called the endothermic reaction. The reaction between barium hydroxide and ammonium chloride is an endothermic reaction. The reaction results in the sharp decrease of temperature.

7. What are the Uses of Barium Hydroxide?

Ans. Barium hydroxide has domestic use. In the lab, it is used to make other barium products. This compound is used to measure the concentration of weak acids. The name of this process is titration. It is also used to treat sewage water. The compound is further used to prepare glass, grease and alkalis.

8. Is Barium Hydroxide Safe?

Ans. Because of the hydroxide, barium hydroxide is corrosive and can damage the skin or eyes. Inhalation of barium hydroxide for a prolonged period of time can result in respiratory ailments. Hence care must be taken while handling barium hydroxide.