salts such as barium chromate and calcium oxalate are generally insoluble in water. the addition of hcl enhance their solubility.

Question

explain why? use chemical equations to highlight your arguments.

Answer 1

The solubility of any substance with a basic anion will be affected by the pH of the solution. The more basic the anion, the stronger this effect.

 

This can be shown with chemical reactions. I'll show this with calcium oxalate. First of all, I expect that calcium oxalate will become more soluble with the addition of an acid because oxalate is the conjugate base of oxalic acid. Below I have shown two chemical reactions (calcium oxalate dissolving and the basic oxalate anion reacting with an acid) and the equation for the overall process.

 

CaC₂O₄ (s) <--> Ca²⁺ (aq) + C₂O₄^2- (aq)

C₂O₄^2- (aq) + 2H⁺ (aq) <--> H₂C₂O₄ (aq)

 

Overall:

 

CaC₂O₄ (s) + 2H⁺ (aq) <--> Ca²⁺ (aq) + H₂C₂O₄ (aq)

 

The acid reacts with the calcium oxalate, resulting in a reduction of the solid calcium oxalate.

 

You can think of this as an application of Le Chatelier's Principle; one of the products of the solubility reaction (the oxalate anion) is being consumed by the added acid. In order the maintain equilibrium (counteract the effect of the applied change), more solid calcium oxalate must dissolve to replenish the consumed oxalate anion.

 

Barium chromate undergoes a similar reaction with the added acid. 

 

 

Answer 2

CL is one of most electronegative after f , it reacts with most of elements such as Ba and Ca. In case it produces ions due to presence of h and o which combines to form water in ratio 2:1 which as a result most of things to it to dissolve. Same is for both.