We have been thought that BaC2O4 is a precipitate when dissolved in H2O.
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?
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).
Thank you!
The reason for the higher solubility of BaC2O4 in an aqueous acidic solution compared to water can be explained by the Le Chatelier's principle.
When BaC2O4 is dissolved in water, it ionizes into Ba2+ and C2O42- ions. However, C2O42- ions have a tendency to react with water to form H2C2O4 (oxalic acid) and OH- ions. This reaction consumes the OH- ions in the solution, shifting the equilibrium towards the right, resulting in a decrease in the solubility of BaC2O4.
In an aqueous acidic solution, there is an excess of H+ ions present. When BaC2O4 is added to the acidic solution, the H+ ions react with the C2O42- ions to form H2C2O4. This reaction consumes the C2O42- ions and shifts the equilibrium towards the right, resulting in increased solubility of BaC2O4.
Therefore, the higher solubility of BaC2O4 in an aqueous acidic solution compared to water is due to the reaction between the C2O42- ions and the excess H+ ions, which helps to dissolve more BaC2O4 into the solution.
The reason for the higher solubility of BaC2O4 in an aqueous acidic solution compared to water is the presence of acid. BaC2O4, also known as barium oxalate, is a sparingly soluble salt. In water, it dissociates into its constituent ions, barium (Ba2+) and oxalate (C2O42-). However, due to the low solubility product constant (Ksp), it remains mostly undissolved, resulting in a precipitate.
In an aqueous acidic solution, the presence of acid (H+) provides an excess of H+ ions in the solution. These H+ ions react with the oxalate ions (C2O42-) to form a more soluble complex ion called dihydrogenoxalate (HC2O4-). The reaction can be represented as:
C2O42- + 2H+ → HC2O4-
The formation of the dihydrogenoxalate ion reduces the concentration of oxalate ions in the solution, which shifts the equilibrium to dissolve more of the sparingly soluble BaC2O4. The solubility of BaC2O4 in the aqueous acidic solution increases due to the formation of this soluble complex ion.
To determine the reason for the higher solubility of BaC2O4 in an aqueous acidic solution, you can perform the following steps:
1. Write the dissociation equation for BaC2O4 in water: BaC2O4(s) ⇌ Ba2+(aq) + C2O42-(aq)
This equation represents the limited dissociation of BaC2O4 in water, resulting in a precipitate.
2. Write the reaction equation for the interaction of oxalate ions with acid in an aqueous acidic solution: C2O42-(aq) + 2H+(aq) → HC2O4-(aq)
This equation shows the reaction between oxalate ions (C2O42-) and hydrogen ions (H+) to form a soluble complex ion, dihydrogenoxalate (HC2O4-).
By comparing these two reactions, you can see that the presence of acid in an aqueous acidic solution leads to the formation of dihydrogenoxalate, increasing the solubility of BaC2O4 compared to water where no acid is present.