Question #71402

1 Answer
Aug 23, 2017

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.