# How do we determine the acidity of a salt?

So dissolve the salt, and measure the $p H$. The salts of strong acids (i.e. lower hydrogen halides, nitric, sulfuric acids) generally give $p H$ neutral solutions.
The salts of weaker acids, e.g. sodium fluoride, give basic solutions. But $p H$ measurement is made first so that we can work out what is going on in solution.