A weak acid, HF, is in solution with dissolved sodium fluoride, NaF. If HCl is added, which ion will react with the extra hydrogen ions from the HCl to keep the pH from changing?

A, OH-

B, Na+

C, F-

D, Na-

E, None of these

c. F1-

Explanation:

In this chemical reaction the expression is:

HF + NaF → NaHF2

The ion that always keep the negative charge is the fluorine with a - 1, if in this mixture there is more positive ions (H1+) the negative ion (F1-) will join with them.

Remember that also the Cl1 - will be free, but the fluorine is more reactive than the fluorine.