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Unformatted text preview: 1. Consider the exchange of energy between a system and its surrounding. If the change in the internal energy of the surroundings is negative, E surr < 0, which of the following is true? (3 pts) Answer: The internal energy of the system increases and the internal energy of the sur- roundings decrease. 2. A system absorbs 300 kJ of heat and does 200 kJ of work on the surroundings. Cal- culate the change in internal energy of the system, E sys . (3 pts) E = q + w = 300 kJ- 200 kJ = 100 kJ Answer: 100 kJ 3. A gas in an expandable container (such as a cylinder and piston arrangement) absorbs 10.0 kJ of heat and has an increase in internal energy of 7.00 kJ. If the external pressure is 1.00 atm and the initial volume is 2.0 L, calculate the final volume of the gas. (5 pts) Calculate the work done by the system. w = E- q = 7- 10 =- 3 kJ =- 29 . 615 L atm Use the work to determine the change in volume. w =- P V- 29 . 615 L atm = (1 . 00 atm ) V Solve the following equation for the final volume V f V = 29 . 615 L = V f- V i = V f- 2 . L Answer: V f =31.6 L 4. When 1.0 mol of a fuel is combusted at a constant pressure of 1.0 atm, it produces 1000 kJ of heat and does 100 kJ of work on its surroundings. Calculate H and E for the combustion of the fuel. (3 pts) H = q at constant pressure H =- 1000 kJ since the system produced (lost) heat. E =- 1000 kJ- 100 kJ Answer: E = -1100 kJ ; H = -1000 kJ 5. The balanced equation for the combustion of butane is given below. If the heat of reaction for butane is H rxn = -2658 kJ, what mass of butane would be required to produce...
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This note was uploaded on 04/19/2011 for the course CHEM 1031 taught by Professor Thomas during the Fall '06 term at Temple.
- Fall '06