Question

What is an amphiprotic species? Name one and write balanced equations that show why it is amphiprotic.

Short answer

An amphiprotic species can donate and accept a proton. HCO₃⁻ is an example: \( \text{HCO}_3^- \to \text{CO}_3^{2-} + \text{H}^+ \) and \( \text{HCO}_3^- + \text{H}^+ \to \text{H}_2\text{CO}_3 \).

Step-by-step solution

Define an Amphiprotic Species

An amphiprotic species is a molecule or ion that can both donate and accept a proton (H⁺), meaning it can act as both an acid and a base.

Identify an Example

A common example of an amphiprotic species is the hydrogen carbonate ion (HCO₃⁻).

Write the Reaction as an Acid

As an acid, the hydrogen carbonate ion (HCO₃⁻) can donate a proton to form carbonate (CO₃²⁻): \( \text{HCO}_3^- \to \text{CO}_3^{2-} + \text{H}^+ \)

Write the Reaction as a Base

As a base, the hydrogen carbonate ion (HCO₃⁻) can accept a proton to form carbonic acid (H₂CO₃): \( \text{HCO}_3^- + \text{H}^+ \to \text{H}_2\text{CO}_3 \)

Confirm Amphiprotic Nature

These equations show that HCO₃⁻ can both donate a proton (acting as an acid) and accept a proton (acting as a base), confirming its amphiprotic nature.

Key concepts

acid-base chemistry

Acid-base chemistry is a branch of chemistry that studies acids, bases, and their reactions. It's central to many processes in both nature and industry.
Acids are substances that can donate a proton (H⁺). Bases, on the other hand, are substances that can accept a proton.
The behavior of acids and bases is crucial to understanding various chemical reactions.
In acid-base chemistry, we often talk about conjugate acid-base pairs. When an acid donates a proton, it becomes its conjugate base. Conversely, when a base accepts a proton, it becomes its conjugate acid.
Amphiprotic species are unique because they can act as both acids and bases. This dual ability makes them fascinating and versatile in reactions.

hydrogen carbonate

Hydrogen carbonate, commonly known as bicarbonate, is an important amphiprotic species in chemistry. Its formula is HCO₃⁻.
Bicarbonate plays a significant role in maintaining pH levels in biological systems, such as the human blood. It acts as a buffer, preventing drastic pH changes.
Bicarbonate can donate a proton, behaving like an acid. When it loses a proton, it forms carbonate (CO₃²⁻):
\( \text{HCO}_3^- \rightarrow \text{CO}_3^{2-} + \text{H}^+ \).
Similarly, bicarbonate can accept a proton, behaving like a base. When it gains a proton, it forms carbonic acid (H₂CO₃):
\( \text{HCO}_3^- + \text{H}^+ \rightarrow \text{H}_2\text{CO}_3 \).
These reactions highlight the dual nature of bicarbonate, proving it can act as both an acid and a base.

proton donation and acceptance

Proton donation and acceptance are key concepts in understanding acid-base chemistry. It revolves around the transfer of protons between molecules or ions.
When a substance donates a proton, it acts as an acid. This process is called proton donation.
For example, hydrogen carbonate (HCO₃⁻) can donate a proton:
\( \text{HCO}_3^- \rightarrow \text{CO}_3^{2-} + \text{H}^+ \).
Conversely, when a substance accepts a proton, it acts as a base. This process is called proton acceptance.
For instance, hydrogen carbonate can accept a proton:
\( \text{HCO}_3^- + \text{H}^+ \rightarrow \text{H}_2\text{CO}_3 \).
Amphiprotic species like HCO₃⁻ are special because they can both donate and accept protons, making them both acids and bases.
This dual functionality makes amphiprotic species important in many chemical processes and reactions.