Cryogenics (PHY 4550 and 6555C)-IHAS Spring 2011 HW-2 Here are some problems to try. The goal is to get you thinking about the material, not to frustrate you. Some of you are better prepared than others to tackles these. So just do your best—the solutions and/or answers are mostly given in your text book--spend a maximum of 5 hours on this assignment and turn it in Feb. 10 in class. Helpful methods, formulae, and date may be found in your text and at: http://pages.uoregon.edu/rjd/vapor1.htm 1. An ideal Linde helium liquefier runs between 1 atm. and 16 atm. at 20 C. What is the liquefaction rate y (2 significant figures)? 2. Calculate the Joule-Thomson coefficient for a gas which obeys a. the ideal gas law: pv=nRT (show that it is 0). b. the Dieterici equation of state: p(v-b)exp(a/vRT)=RT where a and b are constants. What do a and b represent? 3. Normal hydrogen is rapidly liquefied. If no catalyses are present, what is the fraction of para-hydrogen present after 24 hours?