Solubility and explore how interconnected chemical reactions affect each other's balance. These concepts help explain why adding salt to water changes how much will dissolve, or why some metals dissolve better in certain solutions.
Understanding these ideas is key to predicting chemical behavior in real-world situations. From explaining why tap water leaves mineral deposits to optimizing industrial processes, mastering solubility and coupled equilibria unlocks practical chemistry knowledge.
Solubility and Coupled Equilibria
Effects of coupled equilibria
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Involve two or more interconnected chemical reactions that share a common species and influence each other's equilibrium state
Can affect solubility of ionic compounds through where solubility decreases when a common ion is added to the solution ([NaCl](https://www.fiveableKeyTerm:NaCl) and [HCl](https://www.fiveableKeyTerm:HCl))
Formation of complex ions can increase solubility by removing free metal ions from solution and shifting equilibrium towards dissolved state (Ag+ and NH3 forming Ag(NH3)2+)
explains how systems at equilibrium respond to changes in conditions
Calculations for interconnected equilibria
Write balanced chemical equations for each equilibrium reaction
Identify common species shared between reactions
Set up expressions (Ksp, Ka, Kb) for each reaction using equilibrium constant values and initial concentrations
Solve system of equations simultaneously to determine concentrations of all species at equilibrium using techniques like substitution, elimination, or mathematical software
Use the () to calculate the solubility of sparingly soluble salts
pH impact on solubility
Affects solubility of ionic compounds containing acidic or basic anions
Acidic anions (CO32−, PO43−) become protonated at low pH increasing solubility
Basic anions (S2−, OH−) become deprotonated at high pH increasing solubility
Changes pH can also affect formation of complex ions
Ligands that are weak bases (NH3) are more effective at forming complex ions at higher pH values
Analyze impact by:
Identifying acidic or basic anions in ionic compound
Determining effect of pH on protonation state of anions
Considering formation of complex ions and their stability at different pH values
Predicting overall impact on solubility based on combined effects of protonation and complex ion formation
Related Concepts
Equilibrium constant: Quantifies the extent of a reaction at equilibrium
: Process of forming complex ions, which can significantly affect solubility
: Resist changes in pH and can influence solubility of pH-sensitive compounds