Question

Question #71402

Answer 1

The conjugate acid-base pairs are `"HB"("OH")_4//"B"("OH")_4^"-"` and `"H"_3"O"^"+"//"H"_2"O"`.

Explanation:

Write the equation in two steps.

`"B"("OH")_3 + "H"_2"O" → "HB"("OH")_4"`

Then

`underbrace("HB"("OH")_4)_color(red)("acid") + overbrace("H"_2"O")^(color(blue)("base")) ⇌ underbrace("B"("OH")_4^"-")_color(red)("conjugate base") + overbrace("H"_3"O"^"+")^(color(blue)("conjugate acid"))`

A conjugate base is a Brønsted-Lowry acid minus a proton, and a conjugate acid is a Brønsted-Lowry base plus a proton.

Thus, `"HB"("OH")_4` and `"B"("OH")_4^"-"` are a conjugate acid-base pair.

Also, `"H"_3"O"^"+"` and `"H"_2"O"` are a conjugate acid-base pair.