Answer to Question #114774 in Chemistry for tristan

Question

What is the conjugate acid of HCO3−? What is the conjugate base of it?

Answer 1

According to the Brønsted-Lowry theory, an acid can donate a proton (hydrogen cation), and the product of this reaction will be a conjugate base:

acid $\rightarrow$ H⁺ + conjugate base.

And vice versa, a base can accept a proton and form a conjugate acid:

base + H⁺ $\rightarrow$ conjugate acid.

Now let's apply this to HCO₃^-. HCO₃^- can donate a proton, and the product of this reaction is CO₃^2-:

HCO₃^- $\rightarrow$ H⁺ + CO₃^2-.

Therefore, CO₃^2- is its conjugate base. HCO₃^- can also accept a proton, and form H₂CO₃:

HCO₃^- + H⁺ $\rightarrow$ H₂CO₃.

Therefore, H₂CO₃ is its conjugate acid.