chem1008assignment2(feb 10) - heat. As the gas is warmed...

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CHEMISTRY 1008 Name: ___________________ Homework Assignment #2 Due: Noon on Thursday, February 10 1. (3 pts) Identify each energy exchange as primarily heat or work and determine whether the sign of U is positive or negative for the system in each case below: (a) Sweat evaporates from skin, cooling the skin. (The evaporating sweat is the system.) (b) A balloon expands against an external pressure. (The content of the balloon is the system.) (c) An aqueous chemical reaction mixture is warmed with an external flame. (The reaction mixture is the system.) 2. (3 pts) The gas in a piston (defined as the system) is warmed by sitting in the sun and absorbs 655 J of
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Unformatted text preview: heat. As the gas is warmed the piston volume increases by 3.17 L against a pressure of 1.07 atm. What is the change in the internal energy of the gas in the piston? 3. (4 pts) Diborane (B 2 H 6 ) is produced through the reaction here: 2B(s) + 3H 2 (g) B 2 H 6 (g) Determine the H for the synthesis of one mole of diborane given the following data: (a) 2B(s) + 3/2 O 2 (g) B 2 O 3 (s) H = -1273 kJ (b) B 2 H 6 (g) + 3O 2 (g) B 2 O 3 (s) + 3H 2 O(g) H = -2035 kJ (c) H 2 (g) + 1/2 O 2 (g) H 2 O( l ) H = -286 kJ (d) H 2 O( l ) H 2 O(g) H = 44 kJ...
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This note was uploaded on 04/29/2011 for the course CHEM 2080 taught by Professor Davis,f during the Spring '07 term at Cornell University (Engineering School).

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