exam5-key - 1 One joule equals A 4.184 cal 2 2 B 1 kg m/s 2...

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1) One joule equals __________. A) 4.184 cal B) 1 kg ? m 2 /s 2 C) 1 g ? cm/s 2 D) 2 kg E) none of the above 2) The internal energy of a system is always increased by __________. A) a volume compression B) doing work on the system while adding heat to the system C) withdrawing heat from the system D) having the system do work on the surroundings E) adding heat to the system and having the system do work on the surroundings 3) Which one of the following is an exothermic process? A) water evaporating B) ice melting C) boiling soup D) condensation of water vapor E) Ammonium thiocyanate and barium hydroxide are mixed at 25°C: the temperature drops. 4) Calculate the value of E in joules for a system that loses 50 J of heat and has 150 J of work performed on it by the surroundings. A) 50 B) -200 C) -100 D) 100 E) +200 E = q + w if system loses heat, then q = -50J if work is performed on system, then w = +150J E = -50J + 150J = +100J 5) Which of the following is a statement of the first law of thermodynamics? A) E k = ½ M ν 2 B) A negative H corresponds to an exothermic process. C) E = E final - E initial D) 1 cal = 4.184 J (exactly) E) Energy lost by the system must be gained by the surroundings. 6) The reaction below is __________, and therefore heat is __________ by the reaction. 4 Al (s) + 3 O 2 (g) ? 2 Al 2 O 3 (s) H° = -3351 kJ A) exothermic, released B) endothermic, released C) endothermic, absorbed D) exothermic, absorbed Negative H indicates that heat is released. By definition, that is an exothermic reaction. E) thermoneutral, neither released nor absorbed

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7) The value of H° for the reaction below is -482 kJ. Calculate the heat (kJ) released to the surroundings when 12.0 g of CO (g) reacts completely. 2 CO ( g ) + O 2 (g) ? 2 CO 2 ( g ) A) -482 B) 207 C) 103 D) 2.89 x 10 3 E) 65.7 As written, the reaction is for 2 moles CO, thus H° = -482 kJ / 2 mol. Since we specified heat released, the negative sign is unnecessary.
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This note was uploaded on 05/10/2010 for the course CHEM 115 taught by Professor Toto during the Spring '10 term at Marshalltown Community College.

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exam5-key - 1 One joule equals A 4.184 cal 2 2 B 1 kg m/s 2...

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