quiz4 - .\ / Quiz 4B Chemistry 120 October 17. 2007 \ \ (a....

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Unformatted text preview: .\ / Quiz 4B Chemistry 120 October 17. 2007 \ \ (a. [‘3 Relevant Equations: P)! = nRT n = nt/M R = 0.08206 L atm K" moi" efi‘usiontt l/V’fi 1, Multiple Choice (48 pts. -- 6 each) ' h gas do the molecules have the highest average velocity? (See thePeriodic Table for atomic masses.) ) SFS A B) N2 / E 1) Consider four identical 1.0-L flasks containing the following gases each at 25°C and 1 atm pressure. For t wfl C) NH3 D) so2 ‘, E same for all gases ,1 A /7)/Consider four identical 1.0-L flasks containing the following gases each at 25°C and 1 arm pressure. Which gas has the highest densim? See the Periodic Table for atomic masses. (arse / B) N; C) NH; D) so \355/ ’3 ‘fi E) same for all gases 4 "'2 L! Q vapor is 17.5 mm Hg, calculate the mole fraction of hydrogen in the minure. A) 0.0227, @0976 C) 0.100 D) 0.971 E) 0.111 6"": i4? ' l A g 4) Which of the following best describes an unopened can of ice-cold pop? A) an open system B) a closed system C) an isolated system / D) a system at thermal equilibrium I E) the surroundings C 5) Which of the following is an example of an object possessing kinetic energy? A) water at the top of a dam B) a bird perched in a tree C) a ball rolling downhill D) a stick of dynamite E) a be der resting on a cliff E 6) What is the change in internal energy ofa system that has 682 J of work done on it and gives 00485 J of heat? A) -68 J D) —197 J {' EH19” 7“" rear» (.3 is: L): \C T) 7) Which of the following equations correctly describes the reaction illustrating the standard molar enthalpy of formation for C3H304 a) 7 A) 3 C (graphite) + 8 H (g) + 4 0 (g) —’ C3H804 a) B) C3 (5) + 8 (g) + 04 (g) —"’ C3H804 (r) C) 3 C aphite) + 4 H20 (1) ”* C3H804 (1) D) 3 (mphile) + 4 H: (g) + 2 02 (g) —* C3H304 a) E) 3 CH2 (8) + 2 W (“0+ 2 02 (5) a CgHgoa a) B) +682 J C) +1167 J D 8) Given the thermochemical equation: 2 NO (9 + 02 (g) A 2 N02 (8) AH" = —1 14.0 H calculate AHO for the following reaction: N02 (3) —+ NO( 5) + 1/2 02 (8) fl/A) +114.0 kJ B) +57.0 kJ C) -114 kJ (D) 557.0 kJ E) +128 kJ ‘\\,/ 3) A mixture of hydrogen gas and water vapor has a total pressure of 738 mm Hg. Ifthe partial pressure of water 7 ? — )7 F; /I 11. Problems. SHOW YOUR WORK! You may use the equations at the beginning. A. Calculate the molar mass (g/mol) of a vaporized sample of a substance that weighs 0.600 g and occupies 0.197 L at 400 K and has a pressure of 1.00 atm. Hint: n = m/M (l lpts.) w. / at“ M Z m .2: m __ c . \/ wt : new 206) (:13?) CJQ'MQ) Mtg/mo] B, It took 49 sec for 1.0 L of methane, CH4, to effuse through a pin hole. How long will it take for 1.0 L of sulfur dioxide, 80;, to effuse under identical conditions? (Atomic masses: H = 1.0, S = 32.0, 0 = 16.0, C = 12.0) (Recall Graham’s Law.) (10 pts.) / b ""77 IX” 7 - ‘ It 3'. ‘ u 1 7 ‘1 i _ 1 fl Z t c (39%?" '63) ‘0‘ ‘ ii -”“""_‘_ sec / (‘1 44% x 05 C. A 638 g block of lead at an initial temperature of 27.0 °C absorbs 2044 J of heat. What is the final te mperature of the block? The specific heat 0be is 0.128 I g" °C'1. (8 pts.) ._.-- a— ] r I. q:YV'\C(j9 ‘ (I) _. ’1 \v a . r a? 1:2 L1 Us _ ,./ *‘l T- T v— 'I’ w" i T2 : 597.0541: 1111C 3’ ' (gamble ‘ D. Use the following thermochemical equations S (s) + 02 (g) ~+ 503 (5, ° = -296.8 U S (5) + 02 g) —P 503 (g) AHD : .._and Hess” Law to calculate the enthalpy change for the reaction SO: 1g) + V202 (g) —> 803 .5) (12 pts.) AH°= “355/? kJ E. Given the enthalpy of formation data below, what is the AH" of the following reaction ? C2H2(g) + Hug) —> C3H4® A1131 (C2112) = 226.7 kJ/mol; AHf° (C2114) = 52.26 kJ/mol) (11 p15.) "90'2Cn '7 : ...
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quiz4 - .\ / Quiz 4B Chemistry 120 October 17. 2007 \ \ (a....

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