Question

Write equations to illustrate the amphoteric behaviour of \(\left[\mathrm{HCO}_{3}\right]^{-}\) in aqueous solution.

Short answer

- As an acid: \\([ ext{HCO}_3^-] ightarrow [ ext{CO}_3^{2-}] + ext{H}^+\\). - As a base: \\([ ext{HCO}_3^-] + [ ext{H}^+] ightarrow [ ext{H}_2 ext{CO}_3]\\).

Step-by-step solution

Understanding Amphoteric Behaviour

Amphoteric behaviour refers to the ability of a substance to act as both an acid and a base. The bicarbonate ion \([ ext{HCO}_3^-]\) can donate a proton (acting as an acid) or accept a proton (acting as a base).

\\([ ext{HCO}_3^-]\\) Acting as an Acid

To illustrate \( [ ext{HCO}_3^-] \) acting as an acid, it donates a proton (H⁺) to form \( [ ext{CO}_3^{2-}] \) (carbonate ion) and water. The equation is: \[ ext{HCO}_3^- ightarrow ext{CO}_3^{2-} + ext{H}^+ \].

\\([ ext{HCO}_3^-]\\) Acting as a Base

To show \( [ ext{HCO}_3^-] \) acting as a base, it accepts a proton (H⁺) to form carbonic acid \( [ ext{H}_2 ext{CO}_3] \). The equation is: \[ ext{HCO}_3^- + ext{H}^+ ightarrow ext{H}_2 ext{CO}_3 \].

Key concepts

Bicarbonate Ion

The bicarbonate ion, represented as \( \text{HCO}_3^- \), is a crucial component in many chemical reactions, particularly those involving acid-base chemistry. This ion is considered amphoteric, meaning it can act as both an acid and a base. This dual characteristic makes it versatile in chemical reactions, mediating between acidic and basic conditions. It is a critical player in maintaining pH balance in biological systems, which is vital for processes like respiration.

• The bicarbonate ion can donate a proton, behaving like an acid. When this happens, it forms the carbonate ion \( \text{CO}_3^{2-} \), releasing a proton \( \text{H}^+ \).
• Alternatively, it can also accept a proton, acting as a base, to form carbonic acid \( \text{H}_2\text{CO}_3 \).

This behavior demonstrates why the bicarbonate ion is essential in buffering systems, like the one in human blood, where it helps neutralize excess acids or bases, maintaining a stable pH.

Acid-Base Reactions

Acid-base reactions are fundamental processes in chemistry, where an acid donates a proton (\( \text{H}^+ \)) to a base. This transfer of protons can significantly alter the properties of the compounds involved.

• An acid is a proton donor. In an aqueous solution, it releases \( \text{H}^+ \) ions. For example, when \( \text{HCO}_3^- \) acts as an acid, it donates a proton to become \( \text{CO}_3^{2-} \).
• A base is a proton acceptor. When \( \text{HCO}_3^- \) functions as a base, it accepts a proton, converting into the water-soluble carbonic acid \( \text{H}_2\text{CO}_3 \).

These reactions are not only important in theoretical chemistry but are also the basis for practical applications, such as titrations and buffer systems. In the context of bicarbonate ions, their dual role in acid-base reactions exemplifies how substances can alter their behavior based on the conditions, maintaining chemical equilibrium.

Inorganic Chemistry

Inorganic chemistry involves the study of inorganic compounds, typically those that do not include carbon-hydrogen (C-H) bonds. This field covers a wide variety of substances, from salts to metals and minerals. Bicarbonate ions and their reactions are a prime example of inorganic chemistry in action.

• Inorganic chemistry often deals with ionic compounds like \( \text{HCO}_3^- \), which are key components in many natural and industrial processes.
• These compounds are studied for their roles in chemical reactions, their physical properties, and how they interact with other compounds.
• Understanding the behavior of ions like \( \text{HCO}_3^- \) is crucial for applications ranging from environmental chemistry to construction materials and pharmaceutical formulations.

By examining these ion interactions and the underlying principles of acid-base behavior, inorganic chemistry provides essential insights into many chemical processes that are vital to technological advancement and everyday life.