We have been thought that BaC2O4 is a precipitate when dissolved in H2O.

Question

When comparing its solubilty in water and in an aqueous acidic solution,what is the reason for its higher solubility in an aqueous acidic solution than water?

Answer 1

Some oxalats are soluble in water:
K2C2O4
Na2C2O4
(NH4)2C2O4

some oxalates are not soluble in water:
BaC2O4
SrC2O4
CaC2O4
Notice the difference between Group I and group II metals.

Now in acids, oxalates react with the acid to form a new soluble salt, and oxalaic acid, both very soluble.
2HNO3 + BaC2O4 >>>H2C2O4 +Ba(NO3)2

So in acids, the insoluble oxalaic salts "dissolves" to form an acid and soluble salt (often).

Answer 2

Thank you!