1332+Spring+2007+Final - CHEM 1332 SPRING 2007 VERSION 1 NO...

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CHEM 1332 SPRING 2007 VERSION 1 NO CHEATING! 1. How many kilojoules of heat are required to raise the temperature of 484 grams of ethanol (mw = 46) from 0°C to 25°C and then vaporize it completely? (specific heat = 2.46 J/(g °C), ∆H vap = 43.3 kJ/mol) (A) 485 (B) 456 (C) 73.1 (D) 30,200 (E) More information is needed to answer this question. 2. Which of the following compounds is predicted to have the highest enthalpy of vaporization at room temperature? (A) H 2 O (B) CH 4 (C) CCl 4 (D) C 6 H 14 (E) CO 2 3. Which solution would have the largest osmotic pressure? (A) 0.1 M (CH 3 ) 2 CO (acetone) at 25°C (B) 0.1 M C 6 H 12 O 6 at 30°C (C) 0.1 M NH 4 NO 3 at 25°C (D) 0.05 M KBr at 25°C (E) 0.05 M CaCl 2 at 25°C 4. When 0.750 g sample of an unknown substance is dissolved in 20.0 g of benzene, the freezing point of the solution is 4.53 o C. What is the molar mass of the substance? (The normal freezing point of benzene is 5.53 o C and K f is 5.12 o C m -1 .) (A) 180 (B) 870 (C) 7.32 (D) 192 (E) 341 5. Which of the following pairs is most likely to form a heterogeneous mixture? (A) methanol, CH 3 OH, and water, H 2 O (B) hexane, CH 3 (CH 2 ) 4 CH 3 , and octane, CH 3 (CH 2 ) 6 CH 3 (C) potassium chloride, KCl, and carbon tetrachloride, CCl 4 (D) acetic acid, CH 3 COOH, and water, H 2 O (E) an allotrope of iodine, I 7 , and benzene, C 6 H 6 1
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Nitrogen dioxide decomposes to nitrogen and oxygen with a rate constant of 12.5 M -1 s -1 . What is the half-life for the reaction in seconds if [NO 2 ] 0 = 0.00260 M? (A) 10.6 (B) 22.8 (C) 30.8 (D) 42.4 (E) 68.4 7. Determine the rate law for the reaction, NH 4 + + NO 2 - → N 2 + 2 H 2 O given the following data: [NH 4 ] (M) [NO 2 - ] (M) Rate (M/s) 0.010 0.020 0.020 0.015 0.020 0.030 0.010 0.010 0.005 (A) Rate = k[NH 4 + ][NO 2 - ] (B) Rate = k[NH 4 + ] 2 [NO 2 - ] (C) Rate = k[NH 4 + ][NO 2 - ] 2 (D) Rate = k[NH 4 + ] 2 [NO 2 - ] 2 (E) None of the above 8. The activation energy of a reaction is 37.6 kJ/mol and the rate constant is 5.4 x 10 -3 s -1 at 45°C. What is the rate constant at 145°C? (A) 0.16 (B) 5.5 x 10 -3 (C) 8.4 x 10 -3 (D) 0.38 (E) 0.56 9. Based on a reaction profile, the enthalpy of reaction is 430 kJ and the energy of activation for the backward reaction is 156 kJ. What is the energy of activation for the forward reaction? (A) 586 kJ (B) –274 kJ (C) 274 kJ (D) 137 kJ (E) 293 kJ 10. Which plot would not have a slope from which the indicated quantity for the reaction A → Product(s) could be determined? (A) ln [A] vs. t: rate constant for a first order reaction (B) 1/[A] vs. t: rate constant for a second order reaction (C) ln k vs. 1/T (K): activation energy (D) ln k vs. 1/T (K): frequency factor (E) All of these plots would have a slope from which the indicated quantity could be determined. 2
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1332+Spring+2007+Final - CHEM 1332 SPRING 2007 VERSION 1 NO...

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