#pH and Solubility: A Last-Minute Review 🚀

Hey, you've got this! Let's quickly review how pH affects solubility, focusing on the key ideas you'll need for the AP exam. Remember, it's all about how equilibrium shifts with changing conditions.

#The Big Picture: pH, Solubility, and Equilibrium

• pH tells us the concentration of H⁺ (and OH⁻) ions in a solution.
• Solubility is all about how much of a substance dissolves in a solution, and it's an equilibrium process. ⚖️
• Le Chatelier's Principle is our guide: If we change a condition (like pH), the equilibrium will shift to counteract that change.
• The common ion effect can also influence solubility by adding an ion that's already part of the equilibrium.

#### Effects of Acidic Solutions 🍋

• Key Idea: Acidic solutions (high [H⁺]) generally increase the solubility of compounds with basic conjugate bases.
• Why? The H⁺ ions react with the basic conjugate base (A⁻) to form HA, reducing [A⁻], and shifting the equilibrium towards dissolution.
  • $A^- + H^+ \rightleftharpoons HA$
• The weaker the acid, the more basic its conjugate base, and the more its solubility is affected by pH.
• Example: Fe(OH)₃ solubility increases in acidic solutions because H⁺ ions react with OH⁻, reducing [OH⁻] and pushing the dissolution equilibrium to the right.
  • $Fe(OH)_3 \rightleftharpoons Fe^{3+} + 3OH^-$
  • $H^+ + OH^- \rightleftharpoons H_2O$

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