1. 0.075 moles of LiF is added to 1 L of a saturated solution of BaF2. a) write
ID: 906709 • Letter: 1
Question
1. 0.075 moles of LiF is added to 1 L of a saturated solution of BaF2.
a) write the ksp reaction and expression for BaF2. explain
b) what is the molar solubility of the BaF2 in the solution with the added LiF? explain
2. A saturated solution of silver chloride is in equilibrium with solid silver chloride. These reagents are added to seperate portions of the mixture. What effect (if any) with each of them have on the amount of solid silver chloride present? (increase, decrease, no change) and explain why
a. sodium chloride
b. nitric acid
c. ammonia
Explanation / Answer
1. 0.075 moles of LiF is added to 1 L of a saturated solution of BaF2.
a) write the ksp reaction and expression for BaF2. explain
Solution :- Dissociation equation for the BaF2 is as follows
BaF2 ------ > Ba^2+ +2F^-
Ksp is the ion product constant
Ksp equation for the BaF2 is as follows
Ksp = [Ba^2+][F^-]^2
b) what is the molar solubility of the BaF2 in the solution with the added LiF? Explain
Solution :- LiF contains the F^- ion which is the common ion with the BaF2
Therefore it will decrease the solubility of the BaF2
Ksp of the BaF2 = 1.5*10^-6
Now lets calculate the solubility of the BaF2 in 0.075 mol LiF in 1 L solution
Molarity of the LiF = 0.075 mol / 1 L = 0.075 M
Ksp = [Ba^2+] [0.075]^2
1.5*10^-6 = [Ba^2+] [0.075]^2
1.5*10^-6 / [0.075]^2 = [Ba^2+]
2.67*10^-4 = [Ba^2+]
Therefore the solubility of the BaF2 is 2.67*10^-4 mol per L
2. A saturated solution of silver chloride is in equilibrium with solid silver chloride. These reagents are added to seperate portions of the mixture. What effect (if any) with each of them have on the amount of solid silver chloride present? (increase, decrease, no change) and explain why
a. sodium chloride = NaCl contains Cl^- which is the common ion with AgCl therefore NaCl decreases the solubility of the AgCl since we are adding the NaCl to the solution therefore it will shift the equilibrium to left side and result into the formation of the AgCl therefore amount of the AgCl in the solution will increase
b. nitric acid = No change because the HNO3 do not have any common ion with the AgCl therefore it will not affect the amount of AgCl
c. ammonia = Decrease .
Ammonia (NH3) forms the complex ion with the Ag^+ ions therefore it will shift the equilibrium to right side and causes the increase in the solubility of the AgCl
Therefore the amount of AgCl in the solution will decrease.
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