exam1_key - Name: Problem 1 (a-d) (12 points) You want to...

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Unformatted text preview: Name: Problem 1 (a-d) (12 points) You want to heat 1 L of water by 10 °C, and you have the following four methods under consideration: 1 a) You can heat it with a mechanical egg beater that is powered by a 1 kg mass on a rope over a pulley. How far does the mass have to descend "to supply enough work for heating v c ‘ the water? o : k W \Aaak Mung; \“u warm ‘L ’9 “"41” \‘1 \OC WmL‘szbflc-kol. Mgah- 245% locataf “Wvam, ATUMh—r = \L x by 290.3 x MaxWS-EIK‘WE‘CLO K) = \haxqfigmzx (Aqm H. We ‘32. a-‘é ims . \k?’ X Answer: 41G, , S m % b) You can send the water through a solar collector that has an area of 1 m2. How long (in minutes) will it take to heat the water if the sun’s intensity on the collector is 4 J cm”2 min'l? g o\cu\., a I g .r ..-='- \A 695‘: “la Serb e A had Y‘Ctv. Ew- UO COW: ch“ 2 2. , - 2. ‘ \ x \07 gm} AMEXKOSIS — 430’“ XGK‘WV‘B X< , 7’ 3 4xxo“: Answer: ‘ c) d) Name: You can heat it with a charcoal fire. The heat of combustion of graphite (MW = 12 g/mol) is -393 kJ mol'l. How many grams of charcoal will have to burn to supply the heat? 4. area: >4 x‘mc\w\ (1M3 ><\05:\\ *— Made. 4%; a? Charcoal- : M mok. XE - 5T5 no": , WW“; 0418?) 09 Mme.)- How many 500 nm photons. are required to heat the water? +.\‘€X\053 :Nfl % —‘\ 4—\@7<\o">3 XSOOXW “:3 * awogms //,_ \\.09 X \027’ PW‘WS Name: Problem 2 (9 points) You have 0.9 L of water in an insulated (thermally isolated) cup at 20 °C. You add 360 g of ice at —20 °C in the cup tocool the water. Describe the final state of your system in terms of (i) number of moles of ice (ii) number of moles of water and (iii) the final temperature. ~ ' eon—Ir «Mt . 03W d: w or To 06W a} “M 6 M < .W W 7/”) i V, whaécLA— FD \e,\"§ CQLM \“b‘.” W W Me/H, 2é0% ogfm ad: 143K. \EED Win! 5"“ \n at m 0%? wwb 6‘90“? OO‘L’Qr a (a 16°C 4 00C» \. H9002 Max/“V933K‘m‘”\ ( w 0.0\ x X may L,— + n gooqmojslyflmm‘ j_gx\o+3 "(1522835 cw; momma? ‘5 mE‘ TL : Oéc N ; 50W\m+ tam)?” =é0mim ; [OWN/J Answer: Name: Problem 3 (a-c) (15 points) One mole of an ideal monoatomic gas initially at 300 K is expanded from an initial pressure of 10 atm to a final pressure of 1 atm. The molar heat capacity for constant volume for the gas is CV = 2R . Calculate AU, AH, q, w, and the final temperature (Tf) for each of the following 2 paths: (a) An isothermal reversible expansion P; : \om, ‘chz-Mbm CV:%K Name: (b An ex ansion against a constant external ressure of 1 atm in' a thermally isolated p P (adiabatic) system. KOCH; -_ figm- : —\>€ka¢ Ar Pay 3M; P; ‘ Z 0M D" f/ ‘ 2 in 2 ET‘ 2_ AH : BKU‘MD‘Q (m’goa‘i L '5 BIG 2 " r \c \Q— " EX 1%}366 w 3 AOL ‘ T9 = \azL AU :’\-39><\o"3 DH : —Z.?_s xxo33 VVLO U0 5 “\3752H033 (c) Name: An expansion against zero external pressure (against a vacuum) in an adiabatic system. Pex¥30 U) r; O >’V&XEA\I ...
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This note was uploaded on 03/31/2011 for the course CHEM 452 taught by Professor Khalil during the Spring '08 term at University of Washington.

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exam1_key - Name: Problem 1 (a-d) (12 points) You want to...

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