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Barium Hydroxide Formula – Structure, Properties, Uses, Sample Questions

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Barium Hydroxide is the composition of Barium, Hydrogen, Oxygen elements. Barium is a soft, silvery, alkaline earth metal present in group-2 of the periodic table. It is chemically very highly reactive. So it was never found in nature as a free element. It is used in metallurgy and its compounds are used in petroleum production and radiology. Hydrogen is the first element in the periodic table with atomic number 1. It is colorless, odorless, and tasteless gas. Oxygen is a highly reactive nonmetal and oxidizing agent that forms oxides with many elements/compounds.

Barium Hydroxide

The formula for barium hydroxide is Ba(OH)2. Barium Hydroxide is a clear white powder with no smell and is poisonous in nature. Barium Hydroxide is made up of Barium oxide and water. One of the principal compounds of the element Barium is its monohydrate which is also called baryta. So Barium Hydroxide is also termed Baryta. Barium Hydroxide also had other names as Barium di hydroxide and caustic baryta. It is ionic in nature i.e., in an aqueous solution it provides two hydroxide ions per molecule. 

Barium Hydroxide Structure

Properties of Barium Hydroxide

Chemical Formula





White Powder


Slightly soluble in cold water

Molar mass

171.34 g/mol

Melting Point

78° C

Boiling Point

780° C


3.74 g/cm3 when it is in the monohydrate form

2.18 g/cm3 when it is in octahydrate form 



Uses of Barium Hydroxide

  • Barium Hydroxide is used in laboratories to measure the concentration of weak acids.
  • Barium Hydroxide is used in the treatment of sewage water.
  • It is used to manufacture glass, barium soaps, and grease.

Sample Questions

Question 1: How Barium Hydroxide is prepared?


Barium Hydroxide is prepared by dissolving barium oxide with water to give octahydrate form of barium hydroxide which is heated to form monohydrate hydroxide. The equation of this is given by,

BaO + 9H2O —> Ba(OH)2.8H2O

Question 2: Is Barium Hydroxide is safe or dangerous?


Barium Hydroxide is not safe as per the below reasons.

  • Barium Hydroxide damages skin and eyes due to corrosive nature.
  • Inhalation of the Barium Hydroxide for a long period will cause respiratory problems.

Question 3: What happens when barium hydroxide is heated?


When barium hydroxide is heated at 800oC it decomposes to give barium oxide. This Barium Oxide reacts with carbon dioxide to give Barium Carbonate. When ammonium salts react with barium hydroxide, the reaction is extremely endothermic.

Question 4: What is Endothermic Reaction?


When compounds draw heat from nature/surroundings to react, those reactions are called as Endothermic reactions. The reaction between Barium Hydroxide and ammonium chloride is an endothermic reaction which results in sharp decrease in temperature.

Question 5: What is Barium Hydroxide?


The chemical formula for Barium Hydroxide is Ba(OH)2. It is a clear white, solid and granular powder with no smell and is poisonous in nature. Some hazards are created because of barium hydroxide, such as, skin irritation, eye damage, etc.

Question 6: Is Barium Hydroxide ionic?


Yes. In original form, Barium Hydroxide is ionic. Barium Hydroxide is made up of Ba2+ cation and OH anion. So in this form it can’t be neutralized. In order to neutralize it, the number of OH ions are increased to two times.

Last Updated : 20 Dec, 2023
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