Solubility in Acids:

The term ‘solubility’ assign to the property that defines how completely a solute can completely dissolve in a solvent permit together to form a solution. The solubility of an element depends on many components such as temperature, pressure and polarity.

To be more soluble in water, the ions from the salt should be able to react with protons efficiently. In this way, we can say that the salts whose conjugate bases are strong readily dissolve in acid better than in water. This will happens because of strong conjugate bases, which readily reacts with protons.

Examples:

The anion of a salt will react with a H+ ion to form a weak acid, it can be exchanged from the solution by adding an acid.

If we see the example of adding AgI in H+ forms HI and that is a strong acid; therefore, AgI is NOT more soluble in acid than in water.

For Sn(OH)2, adding H+ reacts with OH- to form H2O so YES, we can say it is more soluble in acid than in pure water H2O.

For KClO4, adding H+ forms HClO4 but it is a strong acid so it is NOT more soluble in acid than in pure water.

If CuBr adding H+ forms HBr and that is a weak acid; therefore, CuBr is highly soluble in acid than in water.

For Ag2SO4 in addition of H+ forms HSO4- and that is K2 for H2SO4, there is no k1 since H2SO4 is a strong acid for the first H so we can say it is more soluble in acid than in pure water.

For BaSO3 adding H+ forms HSO3- and that is k2 for k2SO3 there is no k1 since H2SO3 is a strong acid for the first H so we can say BaSO3 is more soluble in acid than in pure water.

Here are some compounds which show solubility in acid. Let’s discuss about these compounds:

These are some salts that will be more soluble in an acidic solution than in pure water are:

1. Ag2SO4

2. Zn (OH)2

3. CuCN

4. RbClO4

5. PbBr2

Solubility of an Acidic solution:

The carbonate rule only applies to salt metal carbonates. Besides this anything with “acid” is apparently soluble in water. Acids are described by its capability to yield ions in solution.

Acidic solutions allow hydronium ions which can protonate the OH- ions of Zn(OH)2 and SO2.

To Determine that whether the given compounds are more soluble in acidic solution than in pure water or not?

Commonly, we can say the solubility of insoluble salts containing anions (conjugate base of a weak acid) like hydroxide, acetate, carbonate, phosphate and sulfide increases in the presence of strong acid than in pure water. Following may be reasons for solubility:

(a) The solubility of compounds is more in acidic solution than in pure water because dissociates in water to give carbonate ion which is a strong conjugate base of the weak carbonic acid.

(b) The solubility is more in acidic solution than in pure water because dissociates in water to give sulfide ion which is a strong conjugate base of weak hydrogen sulfide.

(c) Solid compound of silver chloride dissociates into silver and chloride ion in water. The chloride ion mad is a weak conjugate base of a strong acid and is neutral. So its solubility does not increase in acidic solution.

(d) If Solid dissociates into lead and iodide ion in water. Iodide ion is a weak conjugate base of a strong acid and is neutral. Thus solubility does not increase in acidic solution.

Activity:

How can we determine the auto ionization reaction in Acetic acid?

For each pair we have to choose the salt that would be expected to be more soluble in acidic solution than in pure water?

(a) Hg2 (CH3COO)2 / Hg2Br2 (b) Pb(OH)2 / PbI2 (c) AgI / AgNO2.

In each of the given compounds, we are looking for anions that can react like weak bases. Addition of the acid solution will react with the weakly basic anions, thus driving the solubility expression to the right and helping solubilize the compound (this is an application of Le Chatlier’s principle, which express that removing a product will drive the reaction equilibrium towards increased products). Therefore, we can distinguish the effect of acidic solution for each salt by comparing the behavior of the anions as bases.

In this case, acetate () is a better base than bromide ions, which are the conjugate base of a strong acid and are therefore essentially non-basic. Therefore this salt will be more soluble in acidic solution than that of water.