125pex2 - Copyright RJZ 1 no unauthorized use allowed...

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Copyright RJZ 2/17/12 1 no unauthorized use allowed Chemistry 125 - W12 Practice Midterm 2 This material is copyrighted. Any use or reproduction is not allowed except with the expressed written permission of Dr. Zellmer. If you are taking Chem 125 you are allowed to print one copy for your own use during the quarter you are taking Chem 125 with Dr. Zellmer. You are not allowed to disseminate this material to anyone else during the quarter or in the future.
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Copyright RJZ 2/17/12 2 no unauthorized use allowed 1. An aqueous Na 3 PO 4 solution is prepared by placing 0.3279 grams of Na 3 PO 4 in 100.0 g of water? Assuming an “ideal” ionic solution forms (i.e. no ion-pairing ), what would be the freezing point (°C) of the solution? (K f = 1.86 o C/m) (Formula. Wts.: Na 3 PO 4 = 163.94, H 2 O = 18.02) a) -0.0372 b) 0.0372 c) -0.149 d) 0.149 e) -0.298 2. The vapor pressure of CH 3 OH at 30°C is 160 torr. What mole fraction of glycerol, C 3 H 5 (OH) 3 , (a nonvolatile solute) would be required to lower the vapor pressure to 120 torr? (Atomic weights: C = 12.01, H = 1.008, O = 16.00) a) 0.168 b) 0.188 c) 0.250 d) 0.333 e) 0.750 3. What mass of sucrose, C 12 H 22 O 11 , should be dissolved in 4.00 x 10 2 mL of solution to produce a solution with an osmotic pressure of 494 torr at 25.0°C? (Mol. Wts.: C 12 H 22 O 11 = 342.30, H 2 O = 18.02) a) 2.41 g b) 2.73 g c) 3.05 g d) 3.64 g e) 3.92 g
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Copyright RJZ 2/17/12 3 no unauthorized use allowed 4. A 12.0 g sample of a nonelectrolyte is dissolved in 80.0 g of water. The solution boils at 100.533 °C. What is the molecular weight of the substance? (K b = 0.512°C/m) a) 136 b) 144 c) 150 d) 156 e) 162 5. The balanced equation for the reaction of bromate ion with bromide in acidic solution is given by: BrO 3 ! + 5 Br ! + 6 H + 6 3 Br 2 + 3 H 2 O At a particular instant in time, the value of - ) [Br ! ]/ ) t is 2.0 x 10 ! 3 M/s. What is the value of - ) [H + ]/ ) t in the same units? a) 2.0 x 10 ! 3 b) 7.2 x 10 ! 4 c) 1.2 x 10 ! 3 d) 4.0 x 10 ! 4 e) 2.4 x 10 ! 3 6. A reaction is 3/2 order in A , second order in B and 1/2 order in C . The initial rate of the reaction is 1.0 x 10 -6 M/sec when the initial concentrations are, [A] o = 0.0100 M, [B] o = 0.0200 M and [C] o = 0.0100 M. What is the rate constant (in M -3 s -1 )? a) 0.500 b) 25.0 c) 3.00 x 10 -1 d) 2.00 x 10 -4 e) 35.4
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Copyright RJZ 2/17/12 4 no unauthorized use allowed 7. Given the initial rate data below, what is the rate law for the reaction? 4 Fe 2+ + O 2 + 4 H + 6 4 Fe 3+ + 2 H 2 O Experiment [Fe 2+ ] 0 [O 2 ] 0 [H + ] 0 Initial Rate (M/s) 1 0.001 0.001 0.1 5 x 10 -4 2 0.002 0.002 0.1 8 x 10 -3 3 0.002 0.001 0.2 8 x 10 -3 4 0.002 0.002 0.2 1.6 x 10 -2 a) Rate = k [Fe 2+ ][O 2 ][H + ] b) Rate = k [Fe 2+ ][O 2 ] 2 c) Rate = k [Fe 2+ ] 2 [O 2 ][H + ] 2 d) Rate = k [Fe 2+ ][O 2 ] 2 [H + ] e) Rate = k [Fe 2+ ] 3 [O 2 ][H + ]
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Copyright RJZ 2/17/12 5 no unauthorized use allowed 8. The reaction A 6 B + C is known to be zero-order in A with a rate constant, k, of 5.0 x 10
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This note was uploaded on 02/19/2012 for the course CHEM 125 taught by Professor Zellmer during the Winter '08 term at Ohio State.

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125pex2 - Copyright RJZ 1 no unauthorized use allowed...

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