March 29 - saturated (supersaturated). IF Qsp<KSP too...

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March 29, 2010 Solubility Equilibrium Solid [ionic compound]  cations + anions (Soluble) MX (s)  M+ (aq) + X- (aq) K sp = [M+][X-] K sp = solubility product aka ionization constant or a dissociation constant. Types of salts: 1:2 salt MX 2 (s) - M2+ + 2X- or M2X (s)  2M+ + X2- K sp = [M2+][X-]^2 1:3 salt MX3 (s)  M3+ + 3X- Ksp = [M3+][X-}^3 2:3 salt M2X3 (s)  2M3+ + 3X2- Ksp = [M3+]^2 + [X-]^3 If equilibrium is reached, the solution is saturated [required in order to use K sp ] Solubility of a salt is the maximum saturation. Concentration of ions is solubility.
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How do you know if solution is saturated? Look at the solution, do you see solid sitting on the bottom of the flask? If yes saturated. Compare Q sp to K sp : IF Qsp = Ksp system is at equilibrium. Saturated solution. No further change. IF Qsp>KSP too many products, reaction shifts back to the left. Aka precipitation. Not
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Unformatted text preview: saturated (supersaturated). IF Qsp<KSP too many reactants, reaction shifts to the right, Not saturated. Undersaturated (solution can hold more ion). Wants to dissolve more solid and make more ions. What are the units for solubility? Amount of solute that dissolves /amount of solution it dissolves in a solvent. Grams / L, mg/L, g/100ml. % concentration Molar solubility (moles/Liter) only conc term that appear in Ksp. MgF2. What is the molar solubility of MgF2? K sp = 6.4 * 10^-9. MgF2(aq) Mg2+ + 2F-I | bunch C|-x +x +2x E| bunch-x x 2x Ksp = [Mg 2+ ][F-] 2 Ksp = x*(2x) 2 Ksp = 4x 3 x = (Ksp/4) 3 x = 1.17 x 10-3 M (1.17 x 10-3 ) * (24.3 grams / mole) = 0.0284 grams of Mg 2+ / Liter (0.0284)/(1000g) * 10^6 = 28.4 ppm...
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This note was uploaded on 11/18/2010 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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March 29 - saturated (supersaturated). IF Qsp<KSP too...

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