Is Barium Hydroxide a Strong Base?
A chemical substance that dissociates in water to give OH ions is called a base. The base may be strong or weak depending on the degree of dissociation. A strong base is one that completely dissociates in water to give a high concentration of OH-1 ions. Here in this article, we would discuss a strong base i.e., barium hydroxide Ba(OH)2.
Barium Hydroxide a Strong Base
Barium hydroxide is a group II metal hydroxide. It dissociates completely in water and also acts as a strong base. The barium hydroxide act as a strong base just like other strong bases. It is used in the reactions of hydrolysis of esters and nitriles.
Barium hydroxide gives double the number of OH-1 ions than its original concentration. A large number of OH-1 ions in the aqueous solution of barium hydroxide makes it a strong base. The basicity order of group II metal hydroxides is as follows
Be(OH)2 < Mg(OH)2 < Ca(OH)2 < Sr(OH)2 < Ba(OH)2
Reason of Basicity
Barium hydroxide is sparingly soluble in water but still, it is considered a strong base because it completely ionizes in the water and gives an equal number of OH-1 ions as present in one molecule. you might be wondering that a strong base always accepts a proton according to the bronsted-lowry concept. But barium hydroxide does not seem to absorb a proton. Then how can we call it a strong base?
The OH ions released from Ba(OH)2 accept a proton and produce a water molecule. Hence, barium hydroxide indirectly accepts a proton.
Reactions Involving Barium Hydroxide as a Strong Base
Barium hydroxide is used as a base in the hydrolysis of esters. It is added to catalyze the reaction if it is proceeding too slowly. The alcohol is formed at the end of the reaction.
R2COOR + HOH → R2COO + ROH
Like all other bases, barium hydroxide also neutralizes the acids. It undergoes a neutralization reaction with acids to determine the molarity of unknown specie.
Ba(OH)2 + 2HCl → BaCl2 + 2H2O
Aldol condensation is always carried out in the presence of a strong base. The base abstracts a proton from acetone and ionizes it. This ionized acetone molecule attacks the other acetone molecule and aldol condensation proceeds. Barium hydroxide is usually used in this reaction.
CH3COCH3 + Ba(OH)2 → CH3COCH2- CH3COCH2- + CH3COCH3 → CH3COHCH3CH2COCH3
(4 - hydroxy - 4 - methyl - 2 - pentanone)
Determination of pH of Ba(OH)2
Let us calculate the pH of 0.1M barium hydroxide solution to check if it is a strong base. We know that one molecule of barium hydroxide gives two OH-1 ions. Hence, 0.1M barium hydroxide solution contains 0.2M OH ions. First, we would calculate pOH and then calculate pH.
pOH = - log [OH-1]
pOH = - log [0.2]
pOH = 0.70
pH = 14 – pOH
pH = 14 – 0.70
pH = 13
The above-calculated value of pH confirms that barium hydroxide is a strong base.
Barium hydroxide is a strong base because it dissociates in water completely. It liberates double the amount of OH-1 ions than the number of molecules present. It acts as a strong base in many chemical processes i.e., hydrolysis of esters and many acid-base reactions. It is the strongest of all metal hydroxides of group II.
Related:You can easily understand the uses of barium hydroxide in 6 different ways
Frequently asked questions
Q1: Is barium hydroxide base stronger than ammonia base?
Ans: Barium hydroxide is a strong base than aqueous ammonia. The aqueous solution of barium hydroxide contains double the amount of OH-1 ions than that of aqueous ammonia. That is why barium hydroxide is a strong base than aqueous ammonia.
Q2: How barium hydroxide prevents the neutralization error from occurring?
Ans: The most common neutralization error is the formation of carbonates during the reaction. These carbonates are soluble in water so cannot be separated from the solution. The use of barium hydroxide prevents the hindrance of carbonates because the barium carbonate is insoluble in water and can easily be separated from the solution.
Q3: What are the applications of barium hydroxide?
Ans: It is used as a precursor for the preparation of many other barium derivatives. Other applications are in the sugar industry, oil industry, medical field, and synthetic purposes. Barium hydroxide is also used as an important reagent in many chemical reactions like hydrolysis and neutralization reactions etc.
Q4: What is the effect of heat on barium hydroxide?
Ans: Heat causes the decomposition of barium hydroxide. It decomposes to barium oxide at 800oC. so this method is used to convert barium hydroxide to barium oxide at the laboratory level.