M what is solubility of caf2 s at 25oc s c a 2 ca 2

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Unformatted text preview: M. What is the Ksp for CaF2? M. What is solubility of CaF2 (s) at 25oC (s) C a 2+ Ca 2+ (aq) + 2F - (aq) CaF2 (s) x 2+ 2x −2 K sp = [Ca ][ F ] = x ⋅ (2 x ) = 4 x −4 Check table D-3 D3.9 Ksp = 3.9×10-11 2 = 4 × (4.28 × 10 / 2) = 3.9 × 10 3 3 −11 S ( mol / L ) = [Ca 2+ ] = [ F − ] / 2 = 2.28 × 10 −4 / 2 = 1.14 × 10 −4 M Relationship Relationship between Ksp and Molar Solubility (s) Molar Ca 3 (PO 4 ) 2 (s) 3C a 2+ (aq) + 2 P O 3- (aq) 4 3s 2s K sp = (3s ) 3 ⋅ (2 s ) 2 = 108 s 5 = 1.2 × 10 −26 The deviation of calculated solubility In In principle: Measured solubility ? = In practice: The deviation is due to: Calculated solubility from Ksp ions have low charges Salts : ions do not hydrolyze A Closer Look (17.4) " ion − pairing " effect solubility equilibrium acid - base equilibrium Salts : multiple equilibria hydrolysis equilibrium ... salts dessociate incompletely Solubility Solubility Equilibria Ag + (aq) + Cl - (aq) AgCl(s) K sp = [ Ag + ] ⋅ [Cl − ] = 1.8 × 10 −10 C of ions in a saturated so ln . Q = [ Ag + ] ⋅ [Cl − ] C of ions in any soln. Dissolution Dissolution of an ionic solid in aqueous solution: Q < Ksp Q = Ksp U nsaturated solution, no precipitate S aturated solution, Q > Ksp Supersaturated solution, precipitate w...
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This document was uploaded on 02/26/2014.

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