16.1 Solubility equilibria

Question 1

What is an ionic compound?

Answer 1

Its a compound that will completely dissociate in water.

Question 2

Write the dissociation reaction of CaF2(s)

Answer 2

CaF2(s) -> Ca^2+ (aq) + 2F^- (aq)

Question 3

What type of reaction is Ca^2+ (aq) + 2F^- (aq) -> CaF2(s)

Answer 3

A precipitation reaction.

Question 4

What happen to a solution like this when it reaches equilibrium?

Answer 4

A precipitate will appear (solid that are not dissolved and not dissolvable)

Question 5

What do we call a solution at equilibrium?

Answer 5

We say that it is saturated

Question 6

CaF2(s) → Ca2+ (aq) + 2 F- (aq)

Write the solubility product constant.

Answer 6

Ksp = [Ca2+] [F-]^2

Question 7

What is solubility?

Answer 7

Its the amount of solvent we must add to a given volume of solvent to form a saturated solution.

Question 8

Copper bromide (CuBr) has a measured solubility of 2.0 x 10^-4M at 25ºC. Calculate Kps

Answer 8

4.0 x 10^-8

Question 9

calculate the solubility of MgF2 in H2O at 25ºC. Ksp =7.4*10-11

Answer 9

2.6 x 10^-4 mol/L

Question 10

What is the common ion effect? why does it happen?

Answer 10

When add a substance that has a common ion with the substance we are analyzing, example: add MgF2 into NaF (common ion F+), the solubility of our analyses substance will decrease? This is due to the lechatelier principle. When one side of the equation gets bigger (in this case the product side) the equilibrium shift toward the other side(left in this case) to balance it out.

Question 11

calculate the molar solubility of MgF2 in 0.10M NaF at 25 oC(Ksp= 7.4*10-11)?

Answer 11

7.4 x10^-9 M

Question 12

What pH affects the solution’s solubility and how does it aftect it?

Answer 12

ionic compound with strong base ion is more soluble as the acidity of the ion increases.