Problem 5 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following compounds are formed when \(\mathrm{BCl}_{3}\) is treated with water? (a) \(\mathrm{B}_{2} \mathrm{O}_{3}+\mathrm{HCl}\) (b) \(\mathrm{H}_{3} \mathrm{BO}_{3}+\mathrm{HCl}\) (c) \(\mathrm{B}_{2} \mathrm{H}_{6}+\mathrm{HCl}\) (d) none of these

Step-by-Step Solution

Answer

The compound formed is (b) 0{H}_{3} 0BO}_{3}+0HCl1.

Step 1: Understanding the Reactants

The problem involves the reaction of boron trichloride, 0{BCl}_{3}1, with water. This will help in identifying the possible compounds formed by the hydrolysis reaction.

Step 2: Predicting the Products

0{BCl}_{3}1 is a polar covalent compound and reacts with water in a hydrolysis reaction to produce boric acid 0{H}_{3} 0BO}_{3}1 and hydrochloric acid 0{HCl}1.

Step 3: Checking the Options

Compare the predicted products with the provided options. Based on the prediction, 0{H}_{3} 0BO}_{3}1 and 0HCl1 match option (b).

Step 4: Conclusion

The correct option based on the hydrolysis reaction of 0{BCl}_{3}1 with water is (b) 0{H}_{3} 0BO}_{3}+0HCl1.

Key Concepts

Boron Compounds Reactions

Boron compounds exhibit fascinating chemical behaviors due to the structure and characteristics of boron itself. In nature, boron exists in the form of various borate minerals. However, in laboratory or industrial settings, boron compounds like boron trichloride or boron hydrides are synthesized and used.
When considering reactions involving boron compounds, understanding their electronic configuration is essential. This configuration influences their ability to form bonds and react with other elements. Boron has three electrons capable of forming bonds, making compounds like boron trichloride ( BCl_3 ) unique.
BCl_3 is a polar covalent molecule, owing to its electron-deficient boron atom and a stable chlorine environment. Its reactivity, especially with water, forms the basis for several industrial applications and chemical syntheses, such as the formation of boric acid. Thus, analyzing its reactivity is crucial in predicting and understanding boron compound reactions.

Hydrolysis Reaction Mechanism

The hydrolysis reaction mechanism involving boron trichloride ( BCl_3 ) is a classic example of a hydrolysis reaction in inorganic chemistry. In general, a hydrolysis reaction involves the breaking of bonds in molecules by water. In the case of BCl_3 , the reaction with water leads to the formation of boric acid ( H_3BO_3 ) and hydrochloric acid ( HCl ).
The mechanism can be understood as follows: the lone pairs of electrons on the water molecules attack the electron-deficient boron atom, resulting in the cleavage of the B—Cl bonds. This action facilitates the substitution of chlorine atoms with hydroxyl groups (OH) to form H_3BO_3 . The released chlorine atoms react with hydrogen ions from water to form HCl .
Key steps in hydrolysis:

• Electrophilic attack by water on the boron atom.
• Displacement of chloride ions.
• Formation of boric acid and hydrochloric acid.

This process highlights the vital role of water in transforming chemical compounds, particularly in inorganic reactions.

Inorganic Chemistry Reactions

Inorganic chemistry primarily deals with the behavior, synthesis, and properties of inorganic compounds. Reactions in this field often focus on the exchange or sharing of electrons among a diverse range of elements and compounds, excluding most of organic carbon-containing molecules.
Boron trichloride ( BCl_3 ) reacting with water is a classical inorganic reaction. It showcases how an element or compound behaves in an aqueous environment. When BCl_3 undergoes hydrolysis, it transforms from a gaseous compound to solid and liquid forms, producing H_3BO_3 and HCl in solution.
Key features of inorganic reactions include:

• Variety of bond formations and cleavages.
• Transformation of physical states of elements/compounds.
• Impact of conditions such as temperature and solvent.

These reactions are integral in various applications ranging from synthesis of materials to environmental implications. Understanding such reactions is crucial for chemists and students in predicting behaviors and products of inorganic systems.