question 110 on chem destroyer

[patricklin27]

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can someone explain to me why BaF2 is the answer to this question?

i dont get their explanation. strong acids don't react in acid/base reactions?

and why would the solubility change if a weak acid reacts with a base?

 

[Illfavor]

Which anion, Cl-, Br-, F- or I-, is the strongest base? Strong acids form weak bases, which are inherently less likely to be involved in a reaction. F- is the most basic anion formed, and will react the most/have its reactivity limited the most by an increase or decrease in the pH.

 

[monsieurwise]

You can think like this:
HF is a weak acid
--> F- is a strong base
--> F- will react with water: F- + H2O = HF + OH- (Ba+ will not react because it's a weak acid)
--> you change pH , means changing H+/OH- concentration, let's for example increase H+ concentration
--> H+ will suck up OH-, driving rxn to the right.
--> F- is consumed, making BaF2 even more soluble.
This is why.
I hope that helps =)