Textbook Question
Calculate the molar solubility of PbCrO4 in: (a) Pure Water(d) 1.0 x 10^-3 M K2CrO4
Ch.17 - Applications of Aqueous Equilibria
Chapter 17, Problem 114
Which of the following compounds are more soluble in acidic solution than in pure water? Write a balanced net ionic equation for each dissolution reaction. (a) MnS (b) AgCl (c) BaCO3
Verified step by step guidance1
Identify the compounds that can react with H+ ions in an acidic solution. Compounds that contain anions which are the conjugate bases of weak acids will be more soluble in acidic solutions.
For MnS, recognize that the sulfide ion (S^2-) can react with H+ ions to form H2S, a weak acid. Write the net ionic equation for the dissolution of MnS in acidic solution: \( \text{MnS(s)} + 2\text{H}^+(aq) \rightarrow \text{Mn}^{2+}(aq) + \text{H}_2\text{S(g)} \).
For AgCl, note that the chloride ion (Cl^-) is the conjugate base of a strong acid (HCl), so it does not react with H+ ions. Therefore, AgCl is not more soluble in acidic solution.
For BaCO3, recognize that the carbonate ion (CO3^2-) can react with H+ ions to form H2CO3, which decomposes to CO2 and H2O. Write the net ionic equation for the dissolution of BaCO3 in acidic solution: \( \text{BaCO}_3(s) + 2\text{H}^+(aq) \rightarrow \text{Ba}^{2+}(aq) + \text{CO}_2(g) + \text{H}_2\text{O(l)} \).
Conclude that MnS and BaCO3 are more soluble in acidic solution than in pure water, while AgCl is not.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Solubility and pH
The solubility of certain compounds can be affected by the pH of the solution. In acidic conditions, some salts may dissolve more readily due to the presence of H+ ions, which can react with anions in the salt, effectively removing them from the equilibrium and shifting it towards dissolution.
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Solubility at Buffered pH Example
Common Ion Effect
The common ion effect describes how the solubility of a salt decreases in a solution that already contains one of its constituent ions. In acidic solutions, the addition of H+ can influence the solubility of compounds like carbonates, which react with H+ to form soluble species, thus increasing their solubility.
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Net Ionic Equations
A net ionic equation represents the actual chemical species that are involved in a reaction, excluding spectator ions. Writing a balanced net ionic equation for the dissolution of a compound involves identifying the ions produced in solution and ensuring that the equation is balanced in terms of both mass and charge.
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