Chem 3433 –Problem Set 6 - Due before class on 10/12/11 1. (freshman) Liquid ammonia (b.p. -33.4C) can be used as a refrigerant and heat transfer fluid. How much energy is needed to heat 25 g of NH3(l) (17 g/mol) from -65.0C to -12.0C? Specific heart capacity NH3(l) 4.7 J/(g K) Specific heart capacity NH3(g) 2.2 J/(g K) Heat of vaporization 23.5 kJ/mol 2. Phase equilibrium occurs when the chemical potential of each phase is equal. Thus, gl, which also means that dPVdTSdPVdTSggll. From this starting point show that you can obtainVSdTdP, be sure to define the deltas. For a liquid to gas transition, we can equate Vwith gV. Using an ideal gas, this expression can be integrated to get the standard equation one sees in an undergraduate textbook. 2a. Starting with the equality of the chemical potentials, show how the standard form one sees in an undergraduate textbook is obtained. 2b. Octane has a vapor pressure of 40 torr at 45.1C and 400 torr at 104.0C. What is its heat of vaporization?
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