Exam 1 CH 302 Biberdorf - 282 version number signature Shayak Sen(ss67795 EXAM 1 Biberdorf Class(50203 Water Data Kf = 1.86 C\/m Kb = 0.512 C\/m Cice =

Exam 1 CH 302 Biberdorf - 282 version number signature...

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signature: 282 version number Shayak Sen (ss67795) EXAM 1 Biberdorf Class (50203) Water Data K f = 1 . 86 C/ m K b = 0 . 512 C/ m C ice = 2 . 09 J/g C C water = 4 . 184 J/g C C steam = 2 . 09 J/g C Δ H fusion = 334 J/g Δ H vapor = 2260 J/g Please refer to the back of the bubble sheet for more info. NOTE: Please keep your Exam copy intact (all pages still stapled). You must turn in your exam copy, plus your bubble sheet, scratch paper, and your free response section.
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Version 282 – Exam 1 – biberdorf – (50203) 2 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 4.0points In which of the following will a given sam- ple of PbBr 2 ( K sp = 4 . 6 × 10 6 ) be the least soluble? 1. 100 mL of 0.01 M KOH 2. 100 mL of pure water 3. 100 mL of 0.002 M NaBr 4. 100 mL of 0.05 M HBr correct 5. 100 mL of 0.07 M HCl Explanation: PbBr 2 will have a common ion effect with any solution with Pb 2+ or Br in them. Two of the solutions have Br and those will cause PbBr 2 to be less soluble. The 0.05 M HBr solution has a higher concentration of Br than the NaBr solution, which means it will have the bigger effect on solubility, meaning LESS PbBr 2 will dissolve in that solution. 002 4.0points When 1.28 g of polypeptide are placed in 14.0 L of water at room temperature, the so- lution exerts an osmotic pressure of 4.23 torr. What is the molar mass of the polypeptide? 1. more than 550. g/mol 2. 38.8 g/mol 3. 158. g/mol 4. 402. g/mol correct 5. 388. g/mol 6. 40.1 g/mol 7. less than 25.0 g/mol Explanation: Π = iMRT polypeptide is non electrolyte and i = 1 4.23/760 = (1) M (0.08206)(298.15) M = 0 . 0002275 mol/L x 14L = 0.003185 mol 1.28g/0.003186 mol = 402. g/mol 003 4.0points A 9.386 M aqueous solution of sulfuric acid has a density of 1.5091 g/mL. Calculate the molality of sulfuric acid in this solution. 1. 6.81 m 2. 15.95 m correct 3. 12.84 m 4. 19.62 m Explanation: none 004 4.0points A 250 gram sample of liquid water is heated from 50 C to vapor at 110 C. What are the signs for the change in enthalpy and the change in entropy for this process? 1. Δ H > 0 , Δ S < 0 2. Δ H < 0 , Δ S < 0 3. Δ H = 0 , Δ S > 0 4. Δ H > 0 , Δ S > 0 correct 5. Δ H < 0 , Δ S > 0 Explanation: None 005 4.0points Which of the following shows the right equa- tion for the ion product of iron(III) sulfate?
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