Question

Write a balanced equation for each of the following reactions: (a) Diborane reacts with water to form boric acid and molecular hydrogen. (b) Upon heating, boric acid undergoes a condensation reaction to form tetraboric acid. (c) Boron oxide dissolves in water to give a solution of boric acid.

Short answer

\( (a) \: B_2H_6 + 6H_2O \rightarrow 2H_3BO_3 + 3H_2 \) \( (b) \: 4H_3BO_3 \rightarrow H_2B_4O_7 + 3H_2O \) \( (c) \: B_2O_3 + 3H_2O \rightarrow 2H_3BO_3 \)

Step-by-step solution

Reaction (a): Diborane reacts with water

We need to write a balanced equation for diborane (B2H6) reacting with water (H2O) to form boric acid (H3BO3) and molecular hydrogen (H2). Unbalanced equation: B2H6 + H2O -> H3BO3 + H2 Now, balance the equation by adjusting the coefficients: B2H6 + 6H2O -> 2H3BO3 + 3H2 Balanced equation: B2H6 + 6H2O -> 2H3BO3 + 3H2

Reaction (b): Boric acid undergoes a condensation reaction

We need to write a balanced equation for boric acid (H3BO3) undergoing a condensation reaction to form tetraboric acid (H2B4O7). Unbalanced equation: H3BO3 -> H2B4O7 For a condensation reaction, multiple units of boric acid will combine to form tetraboric acid. In this case, we need 4 units of boric acid to form 1 unit of tetraboric acid and 3 molecules of water, as they are released during the reaction. Balanced equation: 4H3BO3 -> H2B4O7 + 3H2O Reaction (c): Boron oxide dissolves in water to give a solution of boric acid.

Reaction (c): Boron oxide dissolves in water

We need to write a balanced equation for boron oxide (B2O3) dissolving in water (H2O) to form a solution of boric acid (H3BO3). Unbalanced equation: B2O3 + H2O -> H3BO3 Now, balance the equation by adjusting the coefficients: B2O3 + 3H2O -> 2H3BO3 Balanced equation: B2O3 + 3H2O -> 2H3BO3

Key concepts

Balancing Equations

Balancing chemical equations is an essential skill in chemistry. It ensures that the same number of atoms of each element are present on both sides of the equation. This activity is crucial because it follows the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.

To balance an equation, start by listing all the elements involved in the reaction. Then, adjust the coefficients (the numbers in front) of the reactants and products to make the number of atoms equal on both sides. Let's consider an example:

• Begin with the skeleton equation: \( \text{B}_2\text{H}_6 + \text{H}_2\text{O} \rightarrow \text{H}_3\text{BO}_3 + \text{H}_2 \).
• Count the atoms of each element in both the reactants and products.
• Adjust coefficients, starting with the most complex molecule. In this case, balance boron first, then hydrogen, and finally oxygen.

After doing this for each element, you should arrive at the balanced equation: \( \text{B}_2\text{H}_6 + 6\text{H}_2\text{O} \rightarrow 2\text{H}_3\text{BO}_3 + 3\text{H}_2 \). This balanced equation correctly represents the conservation of mass.

Diborane Reaction

Diborane (\( \text{B}_2\text{H}_6 \)) is a unique and interesting compound composed of boron and hydrogen. When diborane reacts with water, it results in the production of boric acid (\( \text{H}_3\text{BO}_3 \)) and molecular hydrogen (\( \text{H}_2 \)).

This reaction can be expressed as:

\[ \text{B}_2\text{H}_6 + 6\text{H}_2\text{O} \rightarrow 2\text{H}_3\text{BO}_3 + 3\text{H}_2 \]
The balanced equation shows that one molecule of diborane reacts with six molecules of water. This reaction is intriguing due to the formation of molecular hydrogen, which can have various applications, such as fuel in hydrogen cells.

• It is highly exothermic, meaning it releases a significant amount of heat.
• Molecular hydrogen is a clean by-product, usable in eco-friendly technologies.

Understanding this reaction is fundamental because it provides insight into how complex hydrides like diborane behave when reacting with water.

Boric Acid

Boric acid (\( \text{H}_3\text{BO}_3 \)) is a weak acid and is often used for its antiseptic properties. It can be formed through various reactions, including the reaction of diborane with water.

Boric acid is not just a product in reactions but a reactant in others, such as its condensation reaction that forms tetraboric acid (\( \text{H}_2\text{B}_4\text{O}_7 \)). The balanced equation for this process is:

\[ 4\text{H}_3\text{BO}_3 \rightarrow \text{H}_2\text{B}_4\text{O}_7 + 3\text{H}_2\text{O} \]

This reaction involves multiple molecules of boric acid combining and releasing water molecules. Important points about boric acid include:

• Safe and commonly used as an insecticide and in eyewashes.
• Participates in condensation reactions, forming more complex borate structures.

Condensation Reaction

Condensation reactions are fascinating chemical processes where two or more molecules combine to form a larger molecule, often releasing a smaller molecule such as water. In the context of boric acid, a condensation reaction can convert boric acid into tetraboric acid.

The equation representing this reaction process is:

\[ 4\text{H}_3\text{BO}_3 \rightarrow \text{H}_2\text{B}_4\text{O}_7 + 3\text{H}_2\text{O} \]

These types of reactions are crucial in organic and inorganic chemistry for building complex molecules.

• The release of water is typical in condensation reactions, hence the term "condensation."
• Such reactions are crucial in creating larger, more complex compounds from simpler ones.

Studying condensation reactions helps understand how small molecules can combine to form materials with unique properties. It demonstrates the versatility and adaptability of chemical reactions in forming diverse substances.