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Ch.17 - Applications of Aqueous Equilibria
Chapter 17, Problem 13

What is the molar solubility of Ag2SO3 in water? The solubility-product constant for silver sulfite is 1.5 x 10^-14 at 25 °C. (a) 1.2 x 10^-7 M (b) 2.0 x 10^-5 M (c) 8.7 x 10^-8 M (d) 1.6 x 10^-5 M

Verified step by step guidance
1
Write the balanced dissolution equation for Ag2SO3: Ag2SO3(s) \rightleftharpoons 2Ag^+(aq) + SO3^{2-}(aq).
Express the solubility product constant (K_{sp}) in terms of the concentrations of the ions: K_{sp} = [Ag^+]^2[SO3^{2-}].
Let the molar solubility of Ag2SO3 be 's'. Then, [Ag^+] = 2s and [SO3^{2-}] = s.
Substitute the expressions for the ion concentrations into the K_{sp} expression: K_{sp} = (2s)^2(s) = 4s^3.
Set the K_{sp} expression equal to the given solubility-product constant and solve for 's': 4s^3 = 1.5 \times 10^{-14}.

Key Concepts

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

Molar Solubility

Molar solubility refers to the maximum concentration of a solute that can dissolve in a solvent at a given temperature, expressed in moles per liter (M). It is a crucial concept in understanding how much of a compound can be present in solution before reaching saturation. In this case, we are determining how much silver sulfite (Ag2SO3) can dissolve in water.
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Solubility Product Constant (Ksp)

The solubility product constant (Ksp) is an equilibrium constant that applies to the dissolution of sparingly soluble ionic compounds. It is defined as the product of the molar concentrations of the ions, each raised to the power of their coefficients in the balanced equation. For Ag2SO3, Ksp helps us relate the concentrations of Ag+ and SO3^2- ions in solution to find the molar solubility.
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Dissociation of Ionic Compounds

When ionic compounds dissolve in water, they dissociate into their constituent ions. For silver sulfite, the dissociation can be represented as Ag2SO3(s) ⇌ 2Ag+(aq) + SO3^2-(aq). Understanding this dissociation is essential for calculating the molar solubility, as it allows us to express the concentrations of the ions in terms of the solubility of the compound.
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