This is from a "effect of pH on the solubility of Ca(OH)2" lab: If excess Ca(NO3)2 were present, what effect would it have on the solubility of Ca9OH)2?
also,
in a "effect of comlex ion formaiton on the solubility of NiCO3" lab": If HCl(aq) were added to the NiCo3 precipitate, rather than NH3 (aq), what effect would it have on the solubility? write a balanced ionic equation for the reaction of HCl 9aq) with NiCO3(s).
Ca(OH)2 is less soluble in Ca(NO3)2 that with no Ca(NO3)2.
NiCO3 reacts with HCl to produce CO2 and H2O.
NiCO3 + 2HCl ==> H2O + CO2 + NiCl2
That's the molecular equation. You can convert that to an ionic equation.
In the "effect of pH on the solubility of Ca(OH)2" lab, if excess Ca(NO3)2 were present, it would not have any effect on the solubility of Ca(OH)2.
To understand why, we need to look at the solubility product constant (Ksp) expression for Ca(OH)2. The Ksp expression is given by the equation:
Ca(OH)2 ⇌ Ca2+ + 2OH-
Ksp = [Ca2+][OH-]^2
In this equation, [Ca2+] represents the concentration of calcium ions and [OH-] represents the concentration of hydroxide ions. The Ksp value is a measure of the solubility of a compound - the higher the Ksp, the more soluble the compound is.
Adding excess Ca(NO3)2, which is a source of calcium ions (Ca2+), does not affect the solubility of Ca(OH)2 because the Ksp expression only depends on the concentration of the ions in solution, not on the source of those ions. The solubility of Ca(OH)2 is determined by the concentration of hydroxide ions ([OH-]), which is controlled by the pH of the solution.
Now, let's move on to the "effect of complex ion formation on the solubility of NiCO3" lab. If HCl(aq) were added to the NiCO3 precipitate instead of NH3(aq), it would increase the solubility of NiCO3.
When HCl(aq) is added to the NiCO3 precipitate, it reacts with carbonate ions (CO32-) to form carbonic acid (H2CO3) and chloride ions (Cl-). The balanced ionic equation for this reaction is:
HCl(aq) + NiCO3(s) -> NiCl2(aq) + H2CO3(aq)
In this reaction, HCl(aq) donates a hydrogen ion (H+) to the carbonate ion (CO32-), resulting in the formation of carbonic acid (H2CO3). The carbonic acid then dissociates into water (H2O) and carbon dioxide (CO2).
The formation of carbonic acid and the subsequent production of carbon dioxide gas drive the reaction to the right, effectively increasing the solubility of NiCO3.