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

Short answer

The correct answer is (b) \(\mathrm{H}_3\mathrm{BO}_3 + \mathrm{HCl}\).

Step-by-step solution

Identify the Reaction

When boron trichloride (\(\mathrm{BCl}_3\)) is treated with water, it undergoes a hydrolysis reaction. The water molecules will react with \(\mathrm{BCl}_3\) to produce boric acid \((\mathrm{H}_3\mathrm{BO}_3)\) and hydrochloric acid \((\mathrm{HCl})\). This is a well-known reaction in inorganic chemistry.

Write the Balanced Equation

Let's write the balanced chemical equation for the reaction between \(\mathrm{BCl}_3\) and water. The equation is:\[ \mathrm{BCl}_3 + 3\mathrm{H}_2\mathrm{O} \rightarrow \mathrm{H}_3\mathrm{BO}_3 + 3\mathrm{HCl} \]This equation shows the formation of boric acid and hydrochloric acid, one molecule of \(\mathrm{BCl}_3\) produces one molecule of \(\mathrm{H}_3\mathrm{BO}_3\) and three molecules of \(\mathrm{HCl}\).

Determine the Correct Answer

Based on the balanced equation, the products formed are \(\mathrm{H}_3\mathrm{BO}_3\) and \(\mathrm{HCl}\). Therefore, the correct compound combination is option (b) \(\mathrm{H}_3\mathrm{BO}_3 + \mathrm{HCl}\). Options (a), (c), and (d) do not reflect the outcome of this reaction.

Key concepts

Boric Acid

Boric acid, known by its chemical formula \( \mathrm{H}_3\mathrm{BO}_3 \), is a weak, monobasic Lewis acid of boron. It is often found in nature in volcanic areas, usually in waters and hot springs.
When it comes to its chemical properties, boric acid acts more like a base despite being an acid due to its ability to accept hydroxide ions. This unique nature is why it's sometimes referred to as a "frustrated acid."
In a reaction context, it is frequently a product of hydrolysis reactions involving boron halides or similar compounds. Boric acid is understated in the grand scheme of inorganic chemistry but plays important roles in:

• Diverse industrial applications, such as a precursor to other chemical compounds
• Acts as an insecticide, antiseptic, or a buffer in chemical settings

Boron Trichloride

Boron trichloride is a chemical compound with the formula \( \mathrm{BCl}_3 \). It is a powerful reagent that is often used in a variety of chemical processes, including organic synthesis and semiconductor production.
Boron trichloride is a colorless, toxic gas with a pungent odor. It reacts vigorously with water, which is the defining attribute in the hydrolysis process leading to the production of boric acid and hydrochloric acid.
Understanding boron trichloride is critical in inorganic chemistry because it demonstrates:

• Exemplary behavior of a Lewis acid;
• Its role as a reagent that can introduce boron into organic molecules.

This ability to introduce boron makes it fundamental in producing boron-containing polymers or other complex chemicals.

Hydrolysis Reaction

The hydrolysis reaction is a fundamental chemical process in which water is used to break bonds in a molecule. In the case of \( \mathrm{BCl}_3 \), the hydrolysis reaction involves the interaction with water to produce boric acid and hydrochloric acid.
This chemical process is essential to understand since it's a common way of reacting inorganic compounds, especially in reactions involving halogens or other reactive groups.
Key aspects of hydrolysis reactions include:

• Reforming products by breaking the original substance's bonds;
• Production often yields simpler or more stable products;
• Input of energy can alter the rate and extent of hydrolysis.

Understanding hydrolysis helps reveal how different stages of reaction can lead to the breakdown or transformation of complex materials into versatile compounds like boric acid.