(1) (50 pts) An ice-skater's skate is in contact with ice over 2 inch length. Assuming the skate width is 3/16 inch and the skater's weight is 160 lb calculate how much the chemical potentials of ice and water (a thin layer of water on the ice surface) at 30 °F changes from normal pressure to the pressure exerted by the skater standing on one skate at the moment? (The densities of water and ice under these conditions are 0.999 g cm^-3 and 0.917 g cm^-3, respectively.)

[Hint: Find the pressure difference between the normal atmospheric pressure and the one exerted by a skater (the blade, the surface, ... etc.) Then figure out how does this affects the ΔG of water and how the ΔG of ice. Compare it if suggest which the process is going to go -- i.e. toward fusion (freezing) or melting.]

2. (25 pts) After finishing a 10 k race the runner's (m = 52.4 kg) body temperature is elevated from 36.6 °C to 37.1 °C. At the race finish stands, she drinks 1.0 L or iced tea (t = 4 °C) which, she feels, cools her down. (a) How much has her total body entropy changed due to the tea ingestion (excluding all other processes)? [Hint: You have to first calculate her final body temperature -- or just copy the number from the KEY to the last exam.]

2. (25 pts) You make 100.0 mL 0.950 % solution of NaCl in water at room temperature; a solution isosalinic (isosalinic = the same amount of salt) with human blood. plasma. Then, it turns out, you have to re-calculate this concentration into molality, m, units. What additional information you need in order to do this? Cite each piece of information separately and briefly explain how you are going to use it.

3. (25 pts) At New Orleans, past Algiers Point, Mississippi delivers 6*10⁵ cf/s of fresh water [http://www.nps.gov/archive/miss/features/factoids/] which, when mixed with seawater, achieves the average salinity of 2.4 % (w/v) in the estuary [http://www.gulfbase.org/bay/view.php?bid=mississippi1]. Assuming that NaCl is the only solute calculate the total daily change in the entropy of mixing caused by the Mississippi flow.

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