A) Find [Zn^2+] and [Fe(CN)6 ^4-] in saturated solution of Zn2Fe(CN)6.

Question

A) Find [Zn^2+] and [Fe(CN)6 ^4-] in saturated solution of Zn2Fe(CN)6.

B) Repeat the above question in 0.1 mM ZnSO4 saturated with Zn2Fe(CN)6.

Answer 1

A. The dissociation of Zn2Fe(CN)6 is:

Zn₂Fe(CN)₆_s --> 2Zn²⁺_aq + Fe(CN)₆^4-
For Zn2Fe(CN)6,
Solubility = s = 3.74x10^-6 M and
K_sp=2.1x10^-16
[Fe(CN)₆^4-] = solubility
[Zn²⁺] = (2)(solubility) <--- see equation above

B. K_sp = [Zn²⁺]²[Fe(CN)₆^4-]
2.1x10^-16 = (0.1)²x
Because of the low solubility we assume that the added concentration of Zn²⁺ is roughly equal to the total Zn²⁺ concentration. "x" represents the ferrocyanide ion concentration which changes because of the equilibrium shift caused by the addition of Zn²⁺ cations. The approximate concentration of Zn²⁺ is 0.1. To get the concentration of Fe(CN)₆^4- solve for x

Answer 2

To find the concentrations of [Zn^2+] and [Fe(CN)6^4-] in a saturated solution of Zn2Fe(CN)6, we need to consider the solubility product constant (Ksp) of Zn2Fe(CN)6 and the stoichiometry of the compound.

A) Find [Zn^2+] and [Fe(CN)6^4-] in a saturated solution of Zn2Fe(CN)6:
1. Start by writing the balanced equation for the dissolution of Zn2Fe(CN)6:
Zn2Fe(CN)6 ⇌ 2Zn^2+ + [Fe(CN)6]^4-

2. Set up an equilibrium expression using the solubility product constant (Ksp):
Ksp = [Zn^2+]^2 × [Fe(CN)6^4-]

3. Since the compound is saturated, we assume that it dissolves completely, meaning the concentration of [Zn^2+] and [Fe(CN)6^4-] are equal.

4. Let's assume x is the concentration of both [Zn^2+] and [Fe(CN)6^4-].

5. Substituting these values into the Ksp expression, we have:
Ksp = (x)^2 × (x)

6. Simplify the equation: Ksp = x^3

7. The Ksp value is typically provided or can be found in a reference book for Zn2Fe(CN)6.

B) Repeat the above question in 0.1 mM ZnSO4 saturated with Zn2Fe(CN)6:
1. Firstly, convert the given concentration to Molarity by dividing by 1000:
0.1 mM = 0.1 × 10^(-3) M = 1 × 10^(-4) M

2. Since we have ZnSO4 in solution, it will partially dissociate into Zn^2+ and SO4^2-. However, the amount of Zn2+ contributed by ZnSO4 will be negligible compared to Zn2Fe(CN)6. Therefore, we can ignore ZnSO4 in the calculations and assume the concentrations of Zn^2+ and [Fe(CN)6]^4- are still equal.

3. Proceed with the same steps as in part A to find the equilibrium concentration of [Zn^2+] and [Fe(CN)6]^4- in the saturated solution of Zn2Fe(CN)6.

By following these steps, you should be able to calculate the concentrations of [Zn^2+] and [Fe(CN)6^4-] in both cases. Note that the actual numerical values will depend on the provided Ksp and the solubility of Zn2Fe(CN)6.