The exact formula of the conjugate acid of the Brønsted-Lowry base HCO₃⁻ is H₂CO₃.
Understanding Brønsted-Lowry Acids and Bases
In Brønsted-Lowry acid-base theory, a base is defined as a proton (H⁺) acceptor, while an acid is a proton donor. When a Brønsted-Lowry base accepts a proton, it forms its corresponding conjugate acid. Conversely, when a Brønsted-Lowry acid donates a proton, it forms its conjugate base.
Formation of a Conjugate Acid
To determine the formula of a conjugate acid from a given Brønsted-Lowry base, you simply add one proton (H⁺) to the base. This process will:
- Increase the number of hydrogen atoms by one.
- Increase the overall charge by +1.
For example, if a base has a charge of -1, its conjugate acid will have a neutral charge (0). If the base is neutral, its conjugate acid will have a +1 charge.
The Conjugate Acid of HCO₃⁻
The bicarbonate ion, HCO₃⁻, is a well-known Brønsted-Lowry base because it readily accepts a proton. When HCO₃⁻ accepts a proton, it undergoes the following reaction:
HCO₃⁻ (base) + H⁺ (proton) → H₂CO₃ (conjugate acid)
This reaction demonstrates how the bicarbonate ion gains a hydrogen atom and its negative charge is neutralized, resulting in the formation of carbonic acid.
Summary Table: Base to Conjugate Acid
| Type | Species | Charge | Proton Accepted | Conjugate Acid |
|---|---|---|---|---|
| Brønsted-Lowry Base | HCO₃⁻ | -1 | +H⁺ | H₂CO₃ |
It's important to note that the bicarbonate ion (HCO₃⁻) is an amphoteric species, meaning it can act as both a Brønsted-Lowry acid and a Brønsted-Lowry base. When it acts as an acid, it donates a proton to form the carbonate ion (CO₃²⁻), which would be its conjugate base. However, for the purpose of this question, focusing on its role as a base, its conjugate acid is indeed H₂CO₃.
To learn more about Brønsted-Lowry theory and acid-base chemistry, you can explore resources like Khan Academy's Chemistry.
