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Unformatted text preview: Chemistry 2740 Spring 2011 Test 2 Time: 50 minutes Marks: 32 Aids allowed: calculator, 8 . 5 × 11-inch formula sheet Useful data: R = 8 . 314 472 J K- 1 mol- 1 To convert degrees Celsius to Kelvin, add 273.15. Instructions: You can answer the questions in any order, but make sure that you clearly label each of your answers with the question number in your exam booklet(s). 1. Name one practical consequence of the third law of thermodynamics. [2 marks] 2. Laboratory freezers used to keep biological samples operate at much lower temperatures than household freezers. One particular freezer keeps a temperature of- 86 ◦ C in a room at 20 ◦ C while consuming 31 MJ/day of electricity. (a) Assuming an ideal refrigerator, how much heat would be expelled into the room per day? [6 marks] (b) How will the heat expelled into the room by the real freezer differ from the figure calculated above? Why? What is the underlying principle? [3 marks] Note: The electricity usage figure given above is the actual figure for a real freezer as measured by the manufacturer....
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This note was uploaded on 03/03/2012 for the course CHEM 2740 taught by Professor Roussel during the Fall '07 term at Lethbridge College.
- Fall '07