PHYS 330 Homework
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   Homework #7: Due Friday, October 10, by 5:30pm.
  1. problem 3.10. Don't forget to answer all the questions in part (d). And yes, I know that this is going backwards just a bit. But since we're using entropy in the Gibbs free energy differential dG=-SdT+VdP, and entropy is such a slippery beast, this review will help.
  2. problem 5.28
  3. Let's extend problem 5.28.
    (a) Still assuming contant T, find the depth below Earth's surface at which the near-surface phase (calcite or aragonite) gives ways to the deeper-earth phase. Use the typical density of Earth as ≈4,000kg/m3.
    (b) Now, let Earth's thermal gradient be (-)20K/km (recall that this will mean that the temperature goes up as the depth goes downward). I want you to start from dG=(-)SdT+VdP, and then make this into a one-variable equation. Then find the depth at which the near-surface phase (calcite or aragonite) gives ways to the deep-earth phase. You must show enough of your numbers here so that I know that you actually calculated this by hand, instead of just having the numerical answer suddenly appear.
   That's all for homework #7.