Question One

The fictitious compound, pandemonium fluoride ( PnF2 ) has a Ksp value in water of 3.091x10^-9 M^3 at room temperature. Calculate the solubility of PnF2 in water. Express your answer in units of molarity.

Question Two

How would you expect the solubility of pandemonium fluoride to vary in water that is warmer than room temperature?

i)The solubility should not change, as the solubility is solely a property of the solute and solvent. It would be invariant with temperature.
ii)The solubility would likely decrease.
iii)The solubility would likely increase.

Why wouldn't you go about this problem the same was as for PbCl2?

Question One

9.17e-4

Question Two
iii)The solubility would likely increase.

Thank you

Answer One

To calculate the solubility of PnF2 in water, we need to use the concept of the solubility product constant (Ksp), which is the equilibrium constant for the dissociation of an ionic compound in water.

The general equation for the dissociation of PnF2 in water is as follows:

PnF2(s) ⇌ Pn2+(aq) + 2F-(aq)

The Ksp value of PnF2 at room temperature is given as 3.091x10^-9 M^3. Since the concentration of Pn2+ is equal to its initial concentration (x), and the concentration of F- ions is twice the initial concentration (2x) due to the stoichiometric coefficient, we can write the Ksp expression:

Ksp = [Pn2+][F-]^2

Substituting the concentrations:

3.091x10^-9 M^3 = x * (2x)^2

Simplifying the equation:

3.091x10^-9 M^3 = 4x^3

Solving for x, the solubility of PnF2 in water:

x = (3.091x10^-9 M^3 / 4)^(1/3)
x ≈ 2.28x10^-3 M

Therefore, the solubility of PnF2 in water is approximately 2.28x10^-3 M.

Answer Two

In general, increasing the temperature usually leads to an increase in the solubility of most solid solutes in water. This trend can be explained by the principle of Le Chatelier's principle.

According to Le Chatelier's principle, increasing the temperature of a system at equilibrium shifts the equilibrium in the direction that consumes heat. In the case of dissolving an ionic compound like PnF2, the dissolution of the solid is an exothermic process, meaning that it releases heat.

When the temperature is increased, the system tries to counteract the increase in heat by shifting the equilibrium in the direction that absorbs heat, which in this case is the dissociation of the solid. This results in an increase in the solubility of PnF2 in water when the temperature is increased above room temperature.

Therefore, the correct answer is iii) The solubility would likely increase.