CHM2046Quiz2 - -3 M e) 7.7 × 10 8 M 4a. If 218 g glucose...

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Version A Quiz 2 ANSWERS UNDERLINED . 1a. Consider the phase diagram shown. Choose the statement below that is TRUE. a) The triple point of this substance occurs at a temperature of 31°C (-56.7°C). b) At 10 atm of pressure, there is no temperature where the liquid phase of this substance would exist. (All 3 phases exist c) The solid phase of this substance is higher in density than the liquid phase. d) The line separating the solid and liquid phases represents the Δ H vap . e) The triple point occurs in region B at -78 o C (-56.7°C). 2a. What is the molality of a solution prepared by dissolving 21.7 g KCl in 225 g H 2 O? molar mass KCl = 74.55 g/mol a) 0.0880 m b) 0.0964 m c) 0.773 m d) 1.29 m e) 2.01 m mol KCl = 21.7 g/74.55 g = 0.291 mol mass water = 0.225 kg molality = 0.291 mol/0.225 kg 3a. What is the equilibrium concentration of N 2 in water when the partial pressure of N 2 is 634 mmHg? k H = 8.2 × 10 -7 M/mmHg S gas = k H P gas = ( 8.2 × 10 -7 M/mmHg)(634 mmHg) a) 1.3 × 10 -9 M b) 5.2 × 10 -4 M c) 1.9 × 10 -2 M d) 1.9 × 10
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Unformatted text preview: -3 M e) 7.7 × 10 8 M 4a. If 218 g glucose (molar mass, 180.02 g/mol) are dissolved in 460 g of water at 30 o C, what is the lowering of the vapor pressure? VP of H 2 O at 30 o C = 31.82 mmHg; molar mass of H 2 O = 18.02 g/mol. mol glucose = 218/180.02 = 1.21 mol mol water = 460/18.02 = 25.5 mol mol fraction glucose = 1.21/(1.21 + 25.5) = 0.0453 Δ VP = 0.0453 × 31.82 mmHg a) 1.4 mmHg b) 4.6 mmHg c) 18 mmHg d) 760 mmHg e) 0.11 mmHg 5a. Vanadium crystallizes in a body centered cubic structure and has an atomic radius of 1.31 × 10-8 cm. Determine the density of vanadium, if the edge length of a bcc structure is 4r/ 3 , and there are 2 vanadium atoms per unit cell. (vanadium = 50.94 g/mol; N A = 6.022 × 10 23 ) a) 3.06 g/cm 3 b) 12.2 g/cm 3 c) 6.09 g/cm 3 d) 2.77 g/cm 3 e) 8.46 g/cm 3 mass = 2 × 50.94/6.022 × 10 23 = 1.692 × 10-22 g V = l 3 = [4 × (1.31 × 10-8 cm)/1.73] 3 = 2.779 × 10-23 cm 3 d e n s i t y = m a s s / V End……………. ....
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This note was uploaded on 09/21/2009 for the course CHM 2046 taught by Professor Dixon during the Spring '08 term at University of Central Florida.

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CHM2046Quiz2 - -3 M e) 7.7 × 10 8 M 4a. If 218 g glucose...

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