Exam 2_07 (1)

# Exam 2_07 (1) - Exam 2 C112 Summer 2007 NAME R = 0.082057...

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Exam 2 C112 Summer 2007 NAME __________________________ R = 0.082057 L atm / mol K = 62.363 mmHg L / mol K = 8.3145 J/ mol K 1. Which statement(s) below is/are TRUE ? Assume ideal solutions. Circle all answers that apply. a) The vapor pressure of a solvent over a solution decreases as its mole fraction increases. b)The solubility of a gas increases as the temperature decreases. c)The vapor pressure of a solvent over a solution is less than that of pure solvent. d)The greater the pressure of a gas over a solution the greater its solubility. e)Ionic solutes dissociate in solution causing a greater effect on colligative properties than non-ionizing solutes at the same concentration. 2. Which of the following samples has the lowest vapor pressure of water above the surface? a) 0.2 m KCl b) 0.2 m Na 2 SO 4 c) mixture: 0.2 m KCl and 0.2 m Na 2 SO 4 d) 0.2 m sugar e) pure water 1

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3. 0.102 g of an unknown compound dissolved in 100.0 mL of water has an osmotic pressure of 28.1 mmHg at 20.0 ° C. Calculate the molar mass of the compound, assuming no ionization occurs. (R values are given in the exam heading) a) 663 g/mol b) 0.872 g/mol c) 1.15 g/mol d) 727 g/mol e) 1.10 × 10 2 g/mol 4. For the following reaction, the rate t H C ] [ 14 6 was found to be 6.2 × 10 3 M/s. C 6 H 14 (g) C 6 H 6 (g) + 4H 2 (g) Determine t H ] [ 2 for this reaction, in units of M/s. a) 6.2 × 10 3 b) 1.6 × 10 3 c) 2.5 × 10 2 d) 1.6 × 10 3 e) 2.5 × 10 2 5. Calculate the boiling point of toluene in a solution containing 0.518 moles of hexane dissolved in 0.500 Kg. of the toluene. The normal boiling point of toluene is 110.6 o C and the boiling point elevation constant, K bp is 3.33 o C/m. van’t Hoff constant for hexane = 1.00 a) 3.45 o C b) 64.1 o C c) 112 o C d) 114 o C e) 175 o C 2
6. For the overall chemical reaction shown below, which one of the following statements can

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Exam 2_07 (1) - Exam 2 C112 Summer 2007 NAME R = 0.082057...

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