Question

Consider the reaction below.

HI + H2O Right arrow. H3O+ + I–

Which is an acid-conjugate base pair?
HI and H2O
H2O and H3O+
H3O+ and I–
HI and I–

Answer 1

HI and I–

HI acts as the acid (donates H+) and becomes I–, its conjugate base. H2O and H3O+ are a conjugate base/conjugate acid pair (H3O+ is H2O with an extra H+), not an acid with its conjugate base in the direction shown.