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Ch.18 - Aqueous Ionic Equilibrium
Chapter 18, Problem 93a

Refer to the Ksp values in Table 18.2 to calculate the molar solubility of each compound in pure water. a. AgBr

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Identify the dissolution equation for AgBr: $\text{AgBr (s)} \rightleftharpoons \text{Ag}^+ (aq) + \text{Br}^- (aq)$.
Write the expression for the solubility product constant ($K_{sp}$) for AgBr: $K_{sp} = [\text{Ag}^+][\text{Br}^-]$.
Let the molar solubility of AgBr be $s$ mol/L. At equilibrium, $[\text{Ag}^+] = s$ and $[\text{Br}^-] = s$.
Substitute the equilibrium concentrations into the $K_{sp}$ expression: $K_{sp} = s \times s = s^2$.
Solve for $s$ by taking the square root of the $K_{sp}$ value: $s = \sqrt{K_{sp}}$.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Solubility Product Constant (Ksp)

The solubility product constant (Ksp) is an equilibrium constant that quantifies the solubility of a sparingly soluble ionic compound. It is defined as the product of the molar concentrations of the ions, each raised to the power of their coefficients in the balanced dissolution equation. For example, for AgBr, Ksp = [Ag+][Br-]. Understanding Ksp is essential for calculating the molar solubility of compounds in water.
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Molar Solubility

Molar solubility refers to the maximum concentration of a solute that can dissolve in a solvent at equilibrium, typically expressed in moles per liter (mol/L). It is directly related to Ksp, as the molar solubility can be derived from the Ksp expression by substituting the concentrations of the ions in terms of the solubility. This concept is crucial for determining how much of a compound can dissolve in water.
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Dissolution Equilibrium

Dissolution equilibrium describes the dynamic balance between the solid phase of a solute and its ions in solution. When a solid ionic compound dissolves, it dissociates into its constituent ions, and the rate of dissolution equals the rate of precipitation at equilibrium. This concept is fundamental for understanding how Ksp and molar solubility relate to the behavior of ionic compounds in solution.
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