The solubility products of AgCl and π΄π3ππ4 are 1.6 Γ 10β10 and 1.8 Γ 10β18, respectively. If π΄π+ is added (without changing the volume) to 1.00 L of a solution containing 0.10 mol πΆπβ and 0.10 mol ππ4 3β, calculate the concentration of π΄π+ions (in mol/L) required to initiate
(a) the precipitation of AgCl and
(b) the precipitation of π΄π3ππ4
Well done
To calculate the concentration of Ag+ ions required to precipitate AgCl and Ag3PO4, we can use the solubility product (Ksp) equation for each compound.
(a) The solubility product (Ksp) equation for AgCl is given as:
Ksp = [Ag+][Cl-]
Let's break down the problem step by step:
Step 1: Write the balanced equation for the dissociation of AgCl:
AgCl(s) β Ag+(aq) + Cl-(aq)
Step 2: Calculate the initial concentration of Ag+ and Cl- ions:
Since we are given that the solution contains 0.10 mol Cl- ions, the initial concentration of Cl- ions is 0.10 mol/L.
The initial concentration of Ag+ ions is zero since no Ag+ ions are initially present.
Step 3: Let's assume that 'x' mol/L of Ag+ ions are required to reach equilibrium and precipitate AgCl.
At equilibrium:
[Ag+] = x mol/L
[Cl-] = 0.10 mol/L
Step 4: Substitute the concentrations into the Ksp equation and solve for x:
Ksp = [Ag+][Cl-]
1.6 Γ 10^(-10) = (x)(0.10)
Solve the equation for x:
x = 1.6 Γ 10^(-10) / 0.10
x β 1.6 Γ 10^(-9) mol/L
Therefore, the concentration of Ag+ ions required to initiate the precipitation of AgCl is approximately 1.6 Γ 10^(-9) mol/L.
(b) The solubility product (Ksp) equation for Ag3PO4 is given as:
Ksp = [Ag+]^3[PO4^3-]
Let's break down the problem step by step:
Step 1: Write the balanced equation for the dissociation of Ag3PO4:
Ag3PO4(s) β 3Ag+(aq) + PO4^3-(aq)
Step 2: Calculate the initial concentration of Ag+ and PO4^3- ions:
Since we are given that the solution contains 0.10 mol PO4^3- ions, the initial concentration of PO4^3- ions is 0.10 mol/L.
The initial concentration of Ag+ ions is zero since no Ag+ ions are initially present.
Step 3: Let's assume that 'y' mol/L of Ag+ ions are required to reach equilibrium and precipitate Ag3PO4.
At equilibrium:
[Ag+] = 3y mol/L
[PO4^3-] = 0.10 mol/L
Step 4: Substitute the concentrations into the Ksp equation and solve for y:
Ksp = [Ag+]^3[PO4^3-]
1.8 Γ 10^(-18) = (3y)^3(0.10)
Solve the equation for y:
y = β(1.8 Γ 10^(-18) / (0.10 * 3^3))
y β 7.60 Γ 10^(-7) mol/L
Therefore, the concentration of Ag+ ions required to initiate the precipitation of Ag3PO4 is approximately 7.60 Γ 10^(-7) mol/L.
To calculate the concentration of Ag+ ions required for the precipitation of AgCl and Ag3PO4, we need to compare the solubility products (Ksp) of the two compounds with the initial concentrations of Cl- and PO4^3- ions in the solution.
(a) Precipitation of AgCl:
The balanced equation for the precipitation of AgCl is:
AgCl(s) β Ag+(aq) + Cl-(aq)
The Ksp expression for AgCl is:
Ksp = [Ag+][Cl-]
Given that the Ksp of AgCl is 1.6 Γ 10^(-10) and the initial concentration of Cl- ions is 0.10 mol/L, we can set up the equation as follows:
1.6 Γ 10^(-10) = [Ag+][0.10]
Solving for [Ag+]:
[Ag+] = (1.6 Γ 10^(-10))/(0.10)
Calculating the concentration of Ag+ required to initiate the precipitation of AgCl will give you the answer.
(b) Precipitation of Ag3PO4:
The balanced equation for the precipitation of Ag3PO4 is:
3AgPO4(s) β Ag3PO4(s) + 3Ag+(aq) + PO4^3-(aq)
The Ksp expression for Ag3PO4 is:
Ksp = [Ag+]^3[PO4^3-]
Given that the Ksp of Ag3PO4 is 1.8 Γ 10^(-18) and the initial concentrations of PO4^3- ions is 0.10 mol/L, we can set up the equation as follows:
1.8 Γ 10^(-18) = [Ag+]^3[0.10]
Solving for [Ag+]:
[Ag+] = (1.8 Γ 10^(-18))^(1/3) / (0.10)
Calculating the concentration of Ag+ required to initiate the precipitation of Ag3PO4 will give you the answer.
Note: It is important to consider the common ion effect when calculating the solubility of compounds in the presence of common ions. The presence of Ag+ ions can reduce the solubilities of AgCl and Ag3PO4.
What (Ag^+) is required to ppt AgCl and Ag3PO4 in separate solutions?
For AgCl it is (Ag^+) = (1.6E-10/0.1) = 1.6E-9 M
For Ag3PO4 it is (Ag^+) = (1.8E-18/0.1)^1/3 = 2.6E-6 M
(a) Therefore, Ag^+ added drop wise to the initial solution will ppt AgCl first when (Ag^+) = 1.6E-9 M and leave Ag3PO4 undisturbed.
(b) When (Ag^+) = 2.62E-6 M the Ag3PO4 will begin ppting.