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Unformatted text preview: Exam II Name Introductory Chemistry 030.101 (Print) La N E 7 First Name
Section I — Professor (3.]. Meyer '
October 24, 2000 Soc. Sec. # SHOW ALL WORK FOR FULL/PARTIAL CREDIT
GIVE FINAL ANSWERS ON THE LINE WHEN INDICATED 191v1 = szz vl/v2= 'n/T2 R = 0.0821 L atm mor‘ K" = 8.314 J mol" K" g = 9.81 m/s2
PV = nRT (P1V1)/Tl = 032V2)/T2 Avogadro’s Number = 6.022 x 1023 p = 1 g/cm3 w = —PmAV q. = nchT = n (3/2)RAT 1 cal = 4.184 J 1 J = 1 kg m2 s *2 1 Pa = 1 kg 111‘1 s;2
q=Mc5ATV cp=cv+Rjzpcquk 1atm=760torr=101,325 Pa 1Latm=101.325]
H=E+PV qp=cpAT’ “WW1 0K=273°C rpm'2' P=pgh uruns = [3RT/M1“2 AB = AH  RTAng For H20: C = 4.18 J K" g" ;AHﬁ,5 = 6.007 kJ mol"; Ava = 170 kJ mol" 5:) 1. Answer the following assuming ideal gas behavior:
a. A sample of C02 gas occupies a volume of 4.5 L and exerts a'pressure 0.67 atm. The volume of the gas is increased decreased to 2.1 L at constant temperature. What is the new pressure of
5/ x the C02(g) ?  v
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P = L '5 gag—“m Answer I. c‘fﬂ
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: L ‘43 «in b) A convenient laboratory source for oxygen of very high purity is the decomposition of potassium
permanganate at 230°C: 2 KMnO4(S) 9 KzMnO4(s) + Mn02(5) + 02(g). Suppose 5.01 L of 02 is needed @ at atmospheric pressure and at a temperature of 22°C. What mass in grams of MO; should be '
reacted at 230°C in order to give the desired volume of 02 when cooled? 0v _ Quad0cm? 3) __ a : ___... __ W...—
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v 3.51; I_ 13' «Ad 331?. _ c) An air bubble with a radius of 8‘Ionm begins its ascent from a depth of 100 m below the surface of the » ocean where the temperature is a frigid 82C. At the surface, the weather is partly cloudy and the
® temperature and pressure are 40:29 and 4%: respectively. What is the volume, in m3, of the air bubble just before it reaches the surface? (Note: The volume of a sphere is 4/3111'3)   3:3 8)
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t, i ? 3‘ P1 1Hfim: La— : LDZa‘i’M ‘ , ’0‘5' 3
V : 531n‘(3'§1J(?m'm) MMIMWSV ‘ ‘= 9.4 X m
‘— 9 0'0"»«3 9:12 Vs: . ' ' ‘ f \ "r T h. ‘ Answer QVX/a m 3 p‘ : 1.010;: 9% i 3
=1.o~++£c;£w(‘—‘%s=) (ﬁhl‘iéell‘wm if“ 1
' ‘ 'l' .5 '7; 1 Introductory Chemistry 030.101 V Name
Section I — Professor Meyer , 2. When N02 is cooled to room temperature, some of it reacts to form the dimer, N204, through the an) reaction: 2 N02 (g) ) N204 (g). Suppose 15.2 g of N02 is placed in a 10.0 L ﬂask at high temperature
" and the'ﬂask is cooled to 25°C. The total pressure is measured to be 0.500 atm. What partial pressures
and mole fractions of N02 and N204 are present? Assume ideal gas behavior. (D  an . @Q
[5.13 New: WM . 0339 m U z. @OMA “W + was: 0,201+
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as. = .304 @Q
6,0893%9 (aﬁ?K> 0 Answer(N204) 0 3. a) The density of an unknown gas at standard temperature and pressure (STP) is 7.41 g/L.
Calculate the molecular weight of the gas. ‘ = M" _ ail—H: (9'03 Mat; 1;) (2h) _ .
m“) 2:63—97 " L 6%) L "‘1‘ Answer 2” 4 hi0 3 lwek.
b) The hydrogenation of an alkene is performed by placing the alkene and a catalyst in a sealed vessel
and attaching a balloon ﬁlled with hydrogen gas. The following hydrogenation of 1,3 cyclohexadiene was performed at STP: C6H3 (1) + 2H2 (g) 9 CGHIZ (1), During the reaction, it was
' observed that the volume of the balloon decreased from a volume of 1.0 L to 0.3 L. How many grams of cyclohexane (C5H12) are produced? How many grams of H2 remain unreacted? "‘ ‘0“?
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= 0.04; M I Introductory Chemistry 030.101 Name ‘ Section I — Professor Meyer 4. (15) A 100.0 g slab of nickel at 100°C is dropped into 6.00 g H20 which is at 100.0°C. What is the
gy‘? What is the ﬁnal ﬁnal temperature reached by nickel and what is its change in internal ener
temperature? What is the change in internal energy for the nickel, the water, and entire system? (C for Nickel is 26.0 J mol'1 K"). Assume no heat is lost to the surroundings.
’ PV m5?— NOgNQYJﬁEZ = mutant “3513: MM,
‘ Lu: L? (25” we} (SIT—3353‘",qu A
(\C \ 0T: "' rm“; CH4) HLO L.Op(‘4_13 0; us I fwin W
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M3 T‘c = Eu nq AEcHzo)
AE(Ni) (4WD 3
: 3 lg K 
TC AE(systern) ( 2 :béi¢t.0 'r 5. (10) a) Given the following two reactions and corresponding enthalpy changes, C0(g) + 8102(5) 9810(9 + C02(g) AHI= +5209 k] AH: +461.05 k]
at: We! , compute the enthalpy and the internal energy changenfor the followmg reaction: 8 CO2(g) + Si3N4(s) '9 3 8102(5) ‘1‘ 2 N20(g) + 8 C0(g) 5' (302(3) + SigN4(5) '9 3 51.0 g + N20(g) + C0(g)
‘ ' A H e bHLe 3 Ni. 3 951.06 + 33203) ; 101093.? 263' AB QUIZSKf 5"“ AH, KT A“? 5 5" AH 323,?kr Introductory Chemistry 030.101 ' Name
Section I — Professor Meyer 6. (5) a) Write an equation describing the ﬁrst law of thermodynamics. A 6 a. 6 14 “J Yb) Which of the terms in the above equation are path ﬁmctions? h‘ if“) 0) Calculate a heat change for 10.0 mol of argon gas (ideal, monatomic) if it is heated in
bomb calorimeter from 250C to 100.0°C. ‘3" g”: m M
5 [one 3083!": 33) (a1)
1 6"{003 _ 7. (20) Suppose 1000.0 mol of an ideal monatomic gas is at a pressure of 2.0 atm and a
' temperature of 100.0°C. It is then expanded at constant pressure until the volume is ﬁve
times its original value. (Use two signiﬁcant ﬁgures for your answers.) 4 a) What is the volume before expansion? Answer I 3099 L—
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b) What is the volume after expansion? 2A6 ‘53:; Answer 7({a05 L
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c) What is the work done on the gas? Answer i ‘2; 000! 0&0 ,3
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d) What is the work done by the gas? Answer :1: many, 00 D;
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" —~© e) What is the total heat transferred? Answer 3°; 0&3; 500 A
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i) What is the change in internal energy? ' :0 3D’gggetm 0003
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. g) What is the enthalpy change? Answer BOﬂEEwSO
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 Fall '08
 Draper
 Chemistry, Thermodynamics, Enthalpy, ideal gas behavior, Professor Meyer

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