Problem 79 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following are formed when \(\mathrm{BCl}_{3}\) is treated with \(\mathrm{NH}_{3}\). (a) \(\mathrm{B}\left(\mathrm{NH}_{2}\right)_{3}\) (b) \(\mathrm{B}_{2}\left(\mathrm{NH}_{3}\right)_{2}\) (c) \(\mathrm{BN}\) (d) All of these

Step-by-Step Solution

Answer

(a) \(\mathrm{B}(mathrm{NH}_{2})_{3}\) is formed.

Step 1: Identify the Reactants

The reactants in this chemical reaction are boron trichloride (\(\mathrm{BCl}_{3}\)) and ammonia (\(\mathrm{NH}_{3}\)). We need to determine what products are formed when these reactants interact.

Step 2: Understand the Reaction

When \(\mathrm{BCl}_{3}\) is treated with \(\mathrm{NH}_{3}\), it generally undergoes a reaction where \(\mathrm{NH}_{3}\) acts as a ligand, coordinating with \(\mathrm{BCl}_{3}\) to form \(\mathrm{BCl}_{3(\mathrm{NH}_{3})}\). This can further interact to form more complex products.

Step 3: Analyze Potential Products

Potential products include:- \(\mathrm{B}(\mathrm{NH}_{2})_{3}\): Formed by replacing each \(\mathrm{Cl}\) atom with \(\mathrm{NH}_{2}\), producing \(\mathrm{B}(\mathrm{NH}_{2})_{3}\) with the release of \(\mathrm{HCl}\).- \(\mathrm{B}_{2}(\mathrm{NH}_{3})_{2}\): Generally not a known stable compound formed by this reaction.- \(\mathrm{BN}\): Can be formed through high-temperature decomposition or polymerization of \(\mathrm{B}(\mathrm{NH}_{2})_{3}\). Typically not the direct result of the given reactants under normal conditions.

Step 4: Determine the Correct Answer

Based on the typical reaction pathways: - Option (a) \(\mathrm{B}(\mathrm{NH}_{2})_{3}\) is a possible product.- Options (b) \(\mathrm{B}_{2}(\mathrm{NH}_{3})_{2}\) and (c) \(\mathrm{BN}\) are not directly formed through the reaction of \(\mathrm{BCl}_{3}\) with \(\mathrm{NH}_{3}\) under typical conditions.Therefore, the correct answer is (a) \(\mathrm{B}(\mathrm{NH}_{2})_{3}\).

Key Concepts

Chemical Reaction

In the world of chemistry, a chemical reaction involves the transformation of reactants into products through a process that rearranges atoms and changes their bonds. When boron trichloride ({BCl}_{3}) reacts with ammonia ({NH}_{3}), a fascinating interaction occurs where nitrogen in ammonia coordinates with boron in {BCl}_{3}.

• This coordination forms a starting complex like {BCl}_{3({NH}_{3})}, often the first step in the more extended reaction series.
• Chemical reactions like these are driven by the tendency of atoms to reach a more stable state.

Understanding how substances transform during reactions is key to mastering chemistry.

Product Formation

Product formation in this context refers to the new chemical substances created during a chemical reaction. When {BCl}_{3} interacts with {NH}_{3}, it can lead to several potential products under different conditions.

• {B}({NH}_{2})_{3}: This compound can be formed by the replacement of chlorine atoms with {NH}_{2} groups, with {HCl} being released as a byproduct.
• {B}_{2}({NH}_{3})_{2}: Although mentioned, this is not a typical stable product from this reaction.
• {BN}: Often only forms under high-temperature conditions through the decomposition and polymerization of precursor compounds.

The main takeaway is that specific reaction pathways and conditions influence which product prevails.

Ligand Coordination

Ligand coordination is a central concept explaining how atoms within molecules form additional bonds, enhancing the stability or forming complexes. In the reaction of {BCl}_{3} with {NH}_{3}, ammonia acts as a ligand:

• Ammonia, possessing a lone pair of electrons, easily coordinates with the electron-deficient boron center in {BCl}_{3}.
• This interaction forms a complex known as a coordination compound. It's an essential step for transforming into other potential reactive products.

Understanding ligand coordination helps explain numerous reactions and structures in chemistry.

Boron-Nitrogen Compounds

Boron-nitrogen compounds, like {B}({NH}_{2})_{3}, emerge under specific reaction conditions when boron trihalides react with nitrogen-containing species. These compounds are notable for their unique bonding characteristics, reminiscent of carbon-based organic compounds.

• The {B}({NH}_{2})_{3} compound is particularly interesting due to its structural and chemical properties.
• These boron-nitrogen compounds are used in various applications, from materials science to advanced electronics, owing to their stability and unique electronic properties.

Exploring the chemistry of boron-nitrogen compounds can pave the way for innovative materials and technologies.