Question

In dilute aqueous solution HF acts as a weak acid. However, pure liquid HF (boiling point = 19.5 °C) is a strong acid. In liquid HF, HNO₃ acts like a base and accepts protons. The acidity of liquid HF can be increased by adding one of several inorganic fluorides that are Lewis acids and accept F– ion (for example, BF3 or SbF5). Write balanced chemical equations for the reaction of pure HNO3 with pure HF and of pure HF with BF3.

a) 3−HNO3+HF→H2O+FNO3−
b) 3−HNO3+HF→H2F++NO3−
c) 3−HNO3+HF→H2O+NO3−
d) 3−HNO3+HF→H2F++FNO3−

Answer 1

In dilute aqueous solution, HF acts as a weak acid. However, in pure liquid HF, HNO3 acts like a base and accepts protons.

The acidity of liquid HF can be increased by adding one of several inorganic fluorides that are Lewis acids and accept F– ion.

Step-by-step explanation:

In dilute aqueous solution, HF acts as a weak acid. However, in pure liquid HF, which has a boiling point of 19.5 °C, HNO3 acts like a base and accepts protons.

The acidity of liquid HF can be increased by adding one of several inorganic fluorides that are Lewis acids and accept F– ion, such as BF3 or SbF5.

The balanced chemical equation for the reaction of pure HNO3 with pure HF is:

3 HNO3 + HF → H2O + FNO3-

The balanced chemical equation for the reaction of pure HF with BF3 is:

HNO3 + 3 HF → H2F+ + NO3-