Achieve #7

[Megan Bundy 2K]

are there rules for classifying salts as basic or acidic? I don't remember Dr. Lavelle explicitly explaining this in class

[Lily Dabrowski 2G]

To classify these you can look at the cations vs ions in the given compound. If the anion is derived from a strong acid, that will make the compound more acidic. If the cation is derived from a strong base, that will make it more basic. If they are both derived from a strong acid or base, then the compound will be neutral. To use the examples from the Achieve question: NH4Br will be acidic; NH4+ is the cation, which does not come from a strong base. Br- is the anion, which comes from the strong acid HBr. LiNO3 will be neutral; Li+ is the cation of strong base LiOH, while NO3- is the anion of strong acid HNO3. Both are derived from a strong acid or base so the whole compound would be neutral. This is at least the logic I used for this problem.

[Leo Chang 2H]

Hi,

For me, the easiest way to classify whether a salt will produce an acidic or basic solution is to look at the salt's chemical formula and determine acidity based on the bonding molecules.

For a salt that has an anion that would produce a strong acid (when bonded with H+), and a cation that would produce a weak base (when bonded with OH-), then the salt would produce an acidic solution.

For a salt that has an anion that would produce a weak acid, and a cation that would produce a strong base, then the salt would produce a basic solution.

For a salt that has an anion and cation that would both produce strong acids and bases, the solution would be neutral.

This is due to the fact that strong acids and bases completely dissociate in aqueous conditions, where as weak acids and bases do not. If a weak acid can be formed from a salt in the water, the OH- concentration would be greater than the H+ concentration, as the protons would end up bonding with the weak acid and not be present completely in their ionized form. The same logic applies for the weak bases, as the OH- would bond to the cation, leaving a surplus of proton concentration.

I hope this helps!