1. CHE 315 – Lecture 10 9/21/05 Equilibrium Review

2. Equilibrium constant K is dimensionless K>1, reaction is favored K>100, reaction is considered to go to completion\ No information about rate or path

3. Equilibrium constant Express aqueous species as Molar Express gaseous species as bar (was atm) Pure solids, pure liquids, and solvents omitted

4. Types K w K sp K a or K b K redox K d β

5. K 1 vs. 1/ K 1

6. Adding equations

7. R=8.314 J/mol-K Thermodynamics: where K comes from ΔG°>0, K 1

8. Solubility Precipitation titrations Electrochemical reference cells Gravimetric analysis Environmental modeling

9. Solubility Product vs. Solubility of Barium?

11. Solubility of Barium in a solution of 0.200 M Ba(NO 3 ) 2 ? Common Ion Effect

12. Separation by precipitation Can Fe 3+ and Mg 2+ be separated as metal hydroxides from a solution that contains 0.1 M of each metal? [Fe 3+ ][OH - ] 3 = 2 x 10 -39 [Mg 2+ ][OH - ] 2 = 7.1 x 10 -12  Looks like Fe will precipitate first  But, will Fe precipitate quantitatively before Mg starts to precipitate?

13. Assume 99.99% removal Concentration of OH - needed to remove 99.99% of iron

14. Will Mg precipitate with [OH - ]? Highest [OH - ] without precipitating Mg Compare with [OH - ] that removes Fe