Jursich practice puiz #1

Jursich practice puiz #1 - C 2 SO 2(g O 2(g 2 SO 3(g...

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Practice Quiz #1 Chem 114 (Jursich) 1) 50.0 mL of 0.0500 M Pb(NO 3 ) 2 is mixed with 40.0 mL of a 0.200 M solution of NaIO 3 and gives 90.0 mL solution. K sp = 2.6 x 10 -13 a) Write K sp expression for Pb(IO 3 ) 2 . b) Determine if a precipitate forms. c) Is solubility affected by pH of the solution? K sp = [Pb 2+ ][IO 3 - ] 2 [Pb 2+ ] = (50 mL/(40+ 50)mL)(0.0500) = 0.0278 M [IO 3 - ] = (40 mL/(40+50) mL)(0.200 M)=0.0889 M Q= (0.0278)(0.0889) 2 = 2.20 x 10 -4 Q >> K so ppt forms. 2) Fill in the blank. ( < , > , = ) a. At equilibrium, the Δ G of reaction ____ = _____ 0. b. In order for an endothermic reaction to be spontaneous, the change of entropy must be ___>_____ 0. c. If Δ G is > 0 then the equilibrium constant, K _<____ 1. d. Exothermic reactions have Δ S surr _>____ 0. e. If q v __>__ 0 the Δ E is > 0. f. In the vaporization of a liquid, g. In condensation of a vapor, Δ H __>____ 0. ΔΗ ___<____ 0 Δ S ___>___ 0. Δ S ___<____ 0 Δ E ___<___ Δ H. Δ E ___>___ Δ H
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3) a) Calculate Δ H, Δ S, Δ G , q p , q v , w , Δ E , K for the following reaction all at 25
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Unformatted text preview: C. 2 SO 2 (g) + O 2 (g) 2 SO 3 (g) Substance Δ H f 0 (kJ/mol) at 25 C S (J/mol-K) at 25 C Δ G f (kJ/mol) at 25 C SO 2 (g) -296.83 248.11 -300.19 SO 3 (g) -395.72 256.65 -371.08 O 2 (g) 0 205.03 0 Δ H = 2(-395.72) – 2(-296.83) – 0 = -197.78 kJ/mol (kJ or kJ per mol ok ; OWL omits /mol) Δ S = 2(256.65)-2(248.11) – (205.03) = -187.95 kJ/mol-K Δ G = Δ H – ΤΔ ΤΔ S = -197,780 –(298 K)(-187.95) = -142 kJ/mol Δ G at 500 C: -197,780 –(773 K)(-187.95) = -52.5 kJ/mol q p = Δ H = -197.78 kJ/mol w = -Δ nRT = -(2-3)RT = (8.3145 J/mol-K)(298.15 K) = 2479.0 J/mol = 2.4790 kJ/mol Δ H = Δ E + Δ nRT so Δ E = Δ H - Δ nRT = -197.78 kJ/mol – (2-3)RT = -197.78 + 2.4790 = -195.30 kJ/mol At 25 C -Δ G = RT ln K K = exp(-Δ G /RT) = exp(-(-142,000 J/mol)/(8.3145)(298 K) K = 7.8 x 10 24 At 500 C K = exp(-Δ G /RT) = exp(-(-142,000 J/mol)/(8.3145)(773 K) K = exp(21.9) = 3.9 x 10 9...
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This note was uploaded on 04/07/2008 for the course CHEM 114 taught by Professor Jursich during the Spring '08 term at Ill. Chicago.

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Jursich practice puiz #1 - C 2 SO 2(g O 2(g 2 SO 3(g...

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