Which of the following salts is more soluble in 1.0 M H+ than in pure water?

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  1 NaCl

  2 MgCl₂

3 NaNO₃

  4 CaCO₃

Answer 1

The salt of a weak acid will be more soluble in acid than in water.

So, NaCl, MgCl2 and NaNO3 are all salts of a strong acid (HCl).

CaCO3 is the salt of a weak acid, H2CO3, so it will be more soluble in H+ than in water.

Why?

Because is you look at the reaction, you have CaCO3 + H+ ==> HCO3 ==> H2CO3 and since this is weak, according to LeChatelier, the reaction will go to the right thus increasing solubility.