Which of the compounds is more soluble in an acidic solution than in pure water?
a. PbBr2
b. CaS
c. Zn(OH)2
d. BaSO3
e. RbClO4
b,c,d are salts that are more soluble in acid solution that in pure water. But the trick is knowing why and how to spot them quickly.
To determine which compound is more soluble in an acidic solution than in pure water, we need to consider the solubility rules for each compound and the behavior of acids.
First, let's look at the solubility rules for each compound:
a. PbBr2 - Most bromides are soluble, except those of silver, mercury(I), and lead(II). So, PbBr2 is soluble in water.
b. CaS - Sulfides are generally insoluble, except those of ammonium, alkali metals, and some alkaline earth metals. So, CaS is insoluble in water.
c. Zn(OH)2 - Hydroxides are generally insoluble, except those of ammonium and alkali metals. So, Zn(OH)2 is insoluble in water.
d. BaSO3 - Sulfites are generally soluble, except those of calcium, strontium, barium, and lead(II). So, BaSO3 is insoluble in water.
e. RbClO4 - Perchlorates are generally soluble. So, RbClO4 is soluble in water.
Next, let's consider the behavior of acids. Acids can ionize in solution and increase the concentration of hydrogen ions (H+) in the solution. This increase in H+ ions can impact the solubility of certain compounds.
Based on the solubility rules and the behavior of acids, the compound that is more likely to be soluble in an acidic solution than in pure water is Zn(OH)2 (option c). This is because hydroxides, such as Zn(OH)2, are generally insoluble in water but can become more soluble in an acidic solution. In an acidic solution, the excess H+ ions react with the OH- ions from the Zn(OH)2 compound, shifting the equilibrium towards the formation of water and increasing the solubility of Zn(OH)2.
Therefore, the answer is option c, Zn(OH)2.