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Chem 300 - Ch 26/#3 Today’s To Do List Metallurgy and K Ellingham Diagrams Ionic Strength & Solubility Life & K.

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Presentation on theme: "Chem 300 - Ch 26/#3 Today’s To Do List Metallurgy and K Ellingham Diagrams Ionic Strength & Solubility Life & K."— Presentation transcript:

1 Chem Ch 26/#3 Today’s To Do List Metallurgy and K Ellingham Diagrams Ionic Strength & Solubility Life & K

2 Metallurgy: Extraction of Metals from Oxides l Reduction with C(s) or CO(g) MO(s) + C(s)  M(s) + CO(g) MO(s) + ½ C(s)  M(s) + ½ CO 2 (g) MO(s) + CO(g)  M(s) + CO 2 (g) l K > 1 l Consider some related reactions

3 4 Oxidation Reactions 1. M(s) + ½ O 2 (g)  MO(s) 2. ½ C(s) + ½ O 2 (g)  ½ CO 2 (g) 3. C(s) + ½ O 2 (g)  CO(g) 4. CO(g) + ½ O 2 (g)  CO 2 (g) l T-Dependence of  r G o : d(  r G o) = - (  r S o )dT

4 Ellingham Diagram

5 Returning to Reduction MO(s) + C(s)  M(s) + CO(g)  r G o =  r G o (3) -  r G o (1) MO(s) + ½ C(s)  M(s) + ½ CO 2 (g)  r G o =  r G o (2) -  r G o (1) MO(s) + CO(g)  M(s) + CO 2 (g)  r G o =  r G o (4) -  r G o (1) When  r G o < 0, the line for rxn (1) lies below the line for rxn (2) – (4).

6 Ellingham Diagram

7 Ionic Strength & Solubility l M + X - (s) = + M z+ + - X z- l Solubility Product constant: K sp = a + + a - - = m + + m - -   ( + + -) l Through   the solubility is affected by other non-chemically-active ions. l ln   = -(1.177 (Z + )(Z - ) I 1/2 )/(1 + I 1/2 ) l ln   = (Z + )(Z - ) I 1/2 (if I <<1)

8 Example: AgCl in 1.5 mmol/kg Ba(NO 3 ) 2 l K a = 1.60 x = [Ag + ][Cl - ] = S 2   2 l I = 3(1.50 x ) + S = S l Solubility = S = (K a 1/2 )/   l What is S of AgCl in plain water? l Ideal solution:   = 1.00  S = (1.60x ) 1/2 = 1.26x10 -5 l What is effect of Ba(NO 3 ) 2 on S of AgCl?

9 With other ions added l 1 st approx: I = x10 -5 = l ln   = -(1.177 I 1/2 )/(1 + I 1/2 ) =   = l S = (K a 1/2 )/   = (1.26x10 -5 )/ = 1.36x10 -5 mol/kg l This value is ~8% higher (measured S = 1.372x10 -5 )

10 A BioPhysChem App. l Ca 3 (PO4) 2 (s) = 3Ca PO 4 3- l K a = [Ca 2+ ] 3 [PO 4 3- ] 2   5 = S 5   5 l Bone/teeth deposition of phosphate/carbonate controlled by K a relationships l S is influenced by presence of other ions

11 Next Time Start Chapter 27 – Kinetic Theory of Gases Average Translational KE & T The Gaussian Distribution & Molecular Speeds


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