Question

Write the balanced reaction of hydroxide ion with hydrofluoric acid, HF, to form fluoride
ion and water. Identify each species as either an acid or a base.

Answer 1

OH- + HF ----> H2O + F-
OH- is base
HF is acid
H2O is neither
F- is base

acid + base gives base + water

Answer 2

Note that in the Bronsted-Lowry theory that
the OH^- is a base and H2O is a conjugate acid.
HF is an acid and F^- is a conjugate base
In the B-L theory an acid gives up a H^+ to produce a conjugate base and a base adds a H^+ to form a conjugate acid.
H2SO4 is an acid and HSO4^- is the conjugate base but in other reactions HSO4^- is an acid and SO4^2- is the conjugate base.