Question

the addition of hydrofluoric acid and ___ to water produces a buffer solution.
a) naf
b) hf
c) nano₃
d) nabr

Explanation:

A buffer solution consists of a weak acid and its conjugate base (or a weak base and its conjugate acid). Hydrofluoric acid (HF) is a weak acid. Its conjugate base is the fluoride ion ($F^-$). Sodium fluoride (NaF) dissociates in water to give $Na^+$ and $F^-$ ions. So, adding HF (weak acid) and NaF (which provides the conjugate base $F^-$) to water will form a buffer.

• Option b (HF) is just more of the weak acid, not providing the conjugate base.
• Option c (NaNO₃) provides $NO_3^-$ which is not related to HF's conjugate base.
• Option d (NaBr) provides $Br^-$ which is also not related to HF's conjugate base.

Answer:

a) NaF