Write the competing equilibrium that will occur when a strong acid is added to the following equilibrium: Ca (aq) + C2O4 (aq) -> CaC2O4 (s)

CaC2O4 ==> Ca^2+ + C2O4^2-

and H^+ + C2O4^2- ==> HC2O4^-
and H^+ + HC2O4^- ==>H2C2O4

For this reason, CaC2O4 is more soluble in an acid solution than in pure H2O.

To determine the competing equilibrium when a strong acid is added to the given equilibrium, we need to understand the effects of the acid on the existing equilibrium.

When a strong acid is added, it increases the concentration of hydrogen ions (H+) in the solution. The increase in H+ ions will shift the equilibrium in a way that reduces the excess of H+ ions. In this case, the H+ ions will react with the anions present in the equilibrium to form a new competing equilibrium.

The anion present in the equilibrium is C2O4 (aq), which can react with H+ ions to form an acid-base reaction. The reaction is as follows:

C2O4 (aq) + 2H+ (aq) -> 2HC2O4- (aq)

In this reaction, C2O4 (aq) acts as a base, accepting H+ ions to form the acid HC2O4- (aq). This new acid-base equilibrium will compete with the existing equilibrium between Ca (aq) and C2O4 (aq).

Therefore, the competing equilibrium, when a strong acid is added to the given equilibrium, is:

Ca (aq) + 2H+ (aq) -> Ca2+ (aq) + 2H+ (aq)

Note that in this new equilibrium, the C2O4 (aq) is consumed by reacting with H+ ions to form HC2O4- (aq), while the Ca (aq) remains unchanged.

When a strong acid is added to the equilibrium Ca (aq) + C2O4 (aq) ⇌ CaC2O4 (s), it will react with the C2O4 ions to form H2C2O4 (oxalic acid) and H2O. The competing equilibrium can be written as:

C2O4 (aq) + 2H+ (aq) ⇌ H2C2O4 (aq)

Please note that the overall equation remains the same, with Ca (aq) still reacting with C2O4 (aq) to form CaC2O4 (s), but the presence of a strong acid shifts the equilibrium of the C2O4 ions towards the formation of H2C2O4 (aq).