For the following problems involving thermodynamic data please consult the database of Robie et al. (1978), which I have uploaded to the course folder. The PDF is searchable, but not perfectly, presumably due to imperfect scanned-text recognition by the search algorithm. The easiest way to search the document is probably to go straight to the index at the end.

1. For the metamorphic reaction [grossular + quartz == anorthite + wollastonite, calculate the Gibbs free energy of reaction and the equilibrium constant at 298.15 K and at 1,000 K (1 bar total pressure). Does increasing temperature favor the formation of the assemblage grossular + quartz, or anorthite + wollastonite?

2. For the reaction converting perovskite and quartz to titanite, determine if the energetically-favored direction of the reaction at 500 K is forward (to titanite) or reverse, if the reaction is exothermic or endothermic, and what molar volume change (∂V_r) occurs during this reaction (at 500 K).

3. Calculate the de Broglie wavelength of an Ar atom moving at 500 m/s (roughly the velocity of air molecules at 25º C). How does this wavelength compare with the radius of an Ar atom?

4. For magnetite oxidation to hematite with O₂, under standard conditions what partial pressure of oxygen gas in air would be buffered by this reaction, assuming no other sources of free molecular oxygen?

5. In a solution containing 0.02 mol/L Na⁺, 0.02 mol/L Cl^-, 0.01 mol/L Ca²⁺, 0.02 mol/L Br^-, and 0.005 mol/L Cu²⁺, determine the ionic strength of the solution and the activity (not concentration) of dissolved Cu²⁺.