Chapter 7: Problem 100
The solubility product of \(\mathrm{A}_{2} \mathrm{X}_{3}\) is \(1.08 \times 10^{-23}\). Its solubility will be: (a) \(1.0 \times 10^{-3} \mathrm{M}\) (b) \(1.0 \times 10^{-4} \mathrm{M}\) (c) \(1.0 \times 10^{-5} \mathrm{M}\) (d) \(1.0 \times 10^{-6} \mathrm{M}\)
Short Answer
Expert verified
(b) \(1.0 \times 10^{-4} \mathrm{M}\).
Step by step solution
01
Understand the Dissolution Reaction
The compound \( \text{A}_2\text{X}_3 \) dissociates in water as follows: \( \text{A}_2\text{X}_3 (s) \rightleftharpoons 2\text{A}^{3+} (aq) + 3\text{X}^{2-} (aq) \). Thus, 2 moles of \( \text{A}^{3+} \) ions and 3 moles of \( \text{X}^{2-} \) ions are produced for every mole of \( \text{A}_2\text{X}_3 \) that dissolves.
02
Express Solubility in Terms of S
Let \( s \) be the solubility of \( \text{A}_2\text{X}_3 \) in mol/L. Therefore, the concentrations at equilibrium will be \( [\text{A}^{3+}] = 2s \) and \( [\text{X}^{2-}] = 3s \).
03
Write the Solubility Product Expression
The solubility product \( K_{sp} \) is given by the expression \( K_{sp} = [\text{A}^{3+}]^2 [\text{X}^{2-}]^3 \). Substituting the concentrations, we have \( K_{sp} = (2s)^2 (3s)^3 \).
04
Simplify and Solve for S
Substitute and simplify: \( K_{sp} = 4s^2 \times 27s^3 = 108s^5 \). Thus, \( s^5 = \frac{K_{sp}}{108} \).
05
Plug in the Known Values
Substitute the known \( K_{sp} \) value: \( s^5 = \frac{1.08 \times 10^{-23}}{108} \).
06
Calculate the Solubility S
Solve for \( s \): \( s = \left(\frac{1.08 \times 10^{-23}}{108}\right)^{1/5} \). Simplifying gives \( s = 1.0 \times 10^{-4} \mathrm{M} \).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Dissolution Reaction
When a compound like \( \text{A}_2\text{X}_3 \) dissolves in water, it undergoes a **dissolution reaction**. This is a process where the solid form of the compound breaks down into its constituent ions in a solution. For \( \text{A}_2\text{X}_3 \), it dissociates into 2 moles of \( \text{A}^{3+} \) ions and 3 moles of \( \text{X}^{2-} \) ions. This dissociation can be represented by the chemical equation:
- \( \text{A}_2\text{X}_3 (s) \rightleftharpoons 2\text{A}^{3+} (aq) + 3\text{X}^{2-} (aq) \)
Equilibrium Concentrations
Equilibrium concentrations are pivotal in understanding how much of each ion is present when a solution reaches a state of balance. During the dissolution of \( \text{A}_2\text{X}_3 \), we let \( s \) represent the solubility, or how much of the solid dissolves. This gives equilibrium concentrations of:
- \( [\text{A}^{3+}] = 2s \)
- \( [\text{X}^{2-}] = 3s \)
Solubility Calculations
Solubility calculations involve finding the maximum concentration of a solute that can dissolve in a solvent at equilibrium. By knowing the solubility product \( K_{sp} \), you can calculate solubility \( s \) in mol/L. For \( \text{A}_2\text{X}_3 \), the \( K_{sp} \) expression is:
- \( K_{sp} = [\text{A}^{3+}]^2 [\text{X}^{2-}]^3 \)
- Substituting give us \( K_{sp} = (2s)^2 \times (3s)^3 \)
- Simplifies to \( K_{sp} = 108s^5 \)
Chemical Equilibrium
**Chemical equilibrium** refers to the state where the rates of the forward and reverse reactions are equal, resulting in no net change in concentrations of reactants and products. For \( \text{A}_2\text{X}_3 \), at equilibrium:
- There is continuous movement of ions between the solid state and the dissolved state
- The concentrations of \( \text{A}^{3+} \) and \( \text{X}^{2-} \) remain constant