P-Block Elements: Diborane

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Questions and Answers

What is the molecular formula of diborane?

BH3

B2H6 (correct)

B2H5

B4H10

Which of the following reactions produces diborane?

B2H6 + O2 → B2O3 + H2O

B2O3 + 6H2 → B2H6 + 3H2O (correct)

3NaBH4 + 4BF3 → 3NaBF4 + 2B2H6 (correct)

2B2H6 + 3H2O → 2B(OH)3 + 6H2

What is the result of diborane reacting with water?

Formation of boric acid (correct)

Formation of ammonia

Formation of boron oxide

Formation of hydrogen gas

What bonding involves the overlap of an SP3 hybrid orbital of one boron atom with an S orbital of hydrogen in diborane?

Sigma (σ) Bond Signup and view all the answers

What is the electronic deficiency in diborane characterized by?

Need for two additional electrons Signup and view all the answers

Which temperature is required for diborane to react with ammonia to form borazole?

200°C Signup and view all the answers

How many total electrons are involved in the bonding of diborane?

12 Signup and view all the answers

What is formed when sodium nitrite is mixed with sodium carbonate and treated with sulfur dioxide?

Sodium salt of hydroxyl amine disulphuric acid Signup and view all the answers

What occurs when hydroxyl amine decomposes at 200°C?

It forms ammonia, nitrogen, and water. Signup and view all the answers

What type of hybridization occurs in the boron atoms of diborane?

sp3 Signup and view all the answers

How does hydroxyl amine react with carbonyl compounds?

It gives corresponding oximes. Signup and view all the answers

Which of the following is NOT an application of hydroxyl amine?

Catalyst for polymerization Signup and view all the answers

What happens when hydroxyl amine reacts with halogens?

It explodes and reduces halogens to the corresponding hydracids. Signup and view all the answers

What is the product formed when boric oxide reacts with carbon and nitrogen?

Boron nitride Signup and view all the answers

Which statement accurately describes the structure of boron nitride?

It has a graphite-like layered structure. Signup and view all the answers

What type of carbide is formed by the reaction of carbon with IA, IIA, or IIIA group elements?

Ionic carbide Signup and view all the answers

What type of ion do Methanides produce during hydrolysis?

C4 ion Signup and view all the answers

Which carbides produce acetylene on hydrolysis?

Acetalides Signup and view all the answers

What is the primary use of boron nitride due to its structure?

For lubrication in high-temperature applications Signup and view all the answers

What is a primary use of carbides in industrial applications?

Preparation of instruments working at high temperatures Signup and view all the answers

Which of the following methods does NOT contribute to the preparation of silicones?

Polymerization of methane Signup and view all the answers

What is the classification of silicones based on their structure?

Linear, Cyclic, and Cross linked Signup and view all the answers

Which process leads to the formation of cyclic silicones?

Elimination of water from terminal –OH groups of linear silicones Signup and view all the answers

What by-product is produced during the hydrolysis of alkyl trichloro silane that leads to cross linked silicones?

Mono chloro silane triol Signup and view all the answers

Which component acts as a catalyst in the aromatic silylation method?

BF3 or BCl3 Signup and view all the answers

What is the product of the reaction between Borazole and hydrochloric acid?

B3N3H9Cl3 Signup and view all the answers

Which of the following boron trihalides is expected to be the most acidic?

BI3 Signup and view all the answers

What hybridization occurs in the boron and nitrogen atoms of Borazole?

SP2 hybridization Signup and view all the answers

What is the result of hydrolysis of Borazole?

Boric acid and ammonia Signup and view all the answers

What is the method for preparing boron nitride?

Heating nitrogen with boron at high temperatures Signup and view all the answers

Study Notes

P-Block Elements

P-block elements have their last electron in P-orbitals.

Boron Family (Group IIIA)

Diborane (B2H6)

Diborane, a significant boron hydride, exhibits unique properties and reactions.
Preparation Methods:
- Reacting boron halides with reducing agents such as sodium borohydride (NaBH4) or Lithium Aluminium Hydride (LAH).
- Reducing B2O3 with H2 at high temperature and pressure using Al+AlCl3 as a catalyst.
Properties:
- Stable in absence of moisture; flammable and decomposes when in contact with water.
- Burns in oxygen to produce boron oxide, releasing heat.
- Reacts with ammonia at high temperatures to form borazole and at low temperatures to create an additive product.
Structure & Bonding:
- Contains 8 atoms and 7 bonds, requiring 14 electrons, but has only 12.
- Electron-deficient due to the absence of 2 electrons.
- Each boron atom undergoes sp3 hybridization, forming sigma (σ) bonds with hydrogen and three-centered two-electron bonds.

Borazole (B3N3H6)

Known as inorganic benzene due to its structural similarity to benzene.
Preparation:
- Formed by the reaction of diborane with ammonia at elevated temperatures.
Properties:
- Exists as a colorless liquid, more reactive than benzene.
- Hydrolysis yields boric acid; reacts with HCl to form B3N3H9Cl3.
Structure:
- Planar configuration with SP2 hybridized B and N atoms; π-bonding involves dative overlap between boron and nitrogen.

Boron Trihalides

Contains BF3, BCl3, BBr3, and BI3; acidity increases with electronegativity of halogen.
Ranking of acidity: BF3 < BCl3 < BBr3 < BI3 due to the presence of partial double bond character in BF3 enhancing resonance.

Boron Nitride (BN)

Synthesized by heating nitrogen with boron or via reaction of boric oxide with carbon.
Exhibits a structure akin to graphite, comprising alternating boron and nitrogen atoms in hexagonal layers.

Carbon Family (Group IV)

Carbides

Formed when carbon reacts with other elements and categorized into ionic, covalent, and interstitial types.
Ionic Carbides:
- Yield hydrocarbons upon hydrolysis; subdivided into methanides, acetalides, and allylides based on products formed.
Covalent Carbides:
- Includes substances like B4C3 and SiC (carborundum).
Interstitial Carbides:
- Formed when carbide ions occupy interstitial sites in metal lattices.

Silicones

Organosilicon polymers characterized by Si-O-Si bonds.
Preparation Methods:
- Direct Si process and aromatic silylation involving reactions with alkyl halides or benzene.
Types:
- Linear Silicones: Derived from hydrolysis of dimethyl dichloro silane.
- Cyclic Silicones: Formed from linear silicones through the elimination of water.
- Cross-linked Silicones: Result from polymerization of hydrolyzed alkyl trichlorosilane.
Properties:
- Heat stability up to 2000°C, non-toxic, and water-repellent.

Hydroxylamine (NH2OH)

Synthesized via the hydrolysis of sodium nitrite in acidic conditions.
Properties:
- Colorless, poisonous, soluble in various solvents, and decomposes at 200°C to yield ammonia and nitrogen.
Reactivity:
- Reduces halogens and reacts with carbonyl compounds to form oximes.
Applications:
- Used in analytical chemistry to identify carbonyl compounds, producing nylon-6, estimating metal ions, and synthesizing dimethyl glyoxime.

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Description

This quiz covers the P-block elements, focusing specifically on the boron family and the compound diborane (B2H6). Explore the preparation methods and reactions involving diborane, as well as its significance in boron chemistry. Test your knowledge on the properties and reactions of these important elements.