Question

Which of the following statements regarding boric acid is false? (1) It acts as monobasic acid. (2) It is soluble in hot water. (3) It is formed by the hydrolysis. (4) It acts as a tribasic acid.

Short answer

Statement (4) is false.

Step-by-step solution

- Understand each statement

Review the properties and characteristics of boric acid to understand each given statement.

- Verify statement (1)

Boric acid acts as a monobasic acid. This is true because boric acid (H3BO3) releases only one proton (H+).

- Verify statement (2)

Check the solubility of boric acid. It is soluble in hot water, indicating that statement (2) is true.

- Verify statement (3)

Determine how boric acid is formed. Boric acid is formed by the hydrolysis of boron compounds such as boron trioxide. Therefore, statement (3) is also true.

- Verify statement (4)

Determine the nature of boric acid's acidity. Boric acid acts as a Lewis acid rather than a typical tribasic acid (which would release three protons). Thus, statement (4) is false.

Key concepts

acid-base chemistry

In acid-base chemistry, acids and bases are substances that can donate or accept protons (H+), respectively. Boric acid (H3BO3) is an interesting case because it doesn't behave like typical acids. Instead of donating protons directly, boric acid acts as a Lewis acid. This means it accepts electron pairs rather than donating protons. Boric acid accepts an OH- ion from water, leading to the release of a proton indirectly. This unique behavior is why boric acid is sometimes referred to as a monobasic acid (since it indirectly leads to the release of just one proton), contrary to what you might expect given its formula (H3BO3). The result of this is the formation of tetraborate ions in aqueous solutions.

solubility of compounds

Solubility refers to the ability of a substance (solute) to dissolve in a solvent to form a homogeneous solution. The solubility of boric acid varies with temperature. It is moderately soluble in cold water, but its solubility increases significantly in hot water. Therefore, when dealing with solubility issues in lab settings, it is advisable to use hot water to dissolve boric acid quickly and effectively. The solubility increase with temperature is a key factor in many chemical processes and applications. Because of its solubility characteristics, boric acid is often used in industrial applications as a cleaning agent and in the manufacture of heat-resistant glass.

Lewis acids

Lewis acids are chemical species that can accept an electron pair. Unlike Brønsted-Lowry acids, which donate protons, Lewis acids are defined by their ability to accept electrons. Boric acid is a classic example of a Lewis acid; it can accept an electron pair from a hydroxide ion to form a tetrahedral borate ion. This property differentiates it from common tribasic acids that release three protons (H+). This acceptance of electron pairs is crucial in many chemical reactions and is fundamental to understanding the behavior of various compounds in solution chemistry. Lewis acids play a vital role in catalysis and complex formation in many industrial and environmental processes.