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Unformatted text preview: brium constant, Keq , at 105°C. One point is earned for setting [AsF3] = [F2] . Note: the point is not earned if the student indicates that [AsF3] = [F2] = [AsF5] . One point is earned for the correct calculation of [AsF3] and [F2] . One point is earned for the correct calculation of Keq . [AsF3] = [F2] = 0.277 × [AsF5]i = 0.277 × 0.0313 M = 0.00867 M
[AsF3 ] [F2 ] [0.00867] [0.00867] = = 0.00333 [0.0226] [AsF5 ] Keq = (d) Calculate the mole fraction of F2(g) in the container at equilibrium. mol AsF5 = 0.0226 M × 10.5 L = 0.237 mol mol F2 = mol AsF3 = 0.00867 M × 10.5 L = 0.0910 mol mol fraction F2 = = OR mol fraction F2 =
0.00864 = 0.217 0.00864 + 0.00864 + 0.0226
mol F2 mol F2 + mol AsF3 + mol AsF5 0.0910 = 0.217 0.0910 + 0.0910 + 0.237 One point is earned for the correct calculation of the mole fraction of F2(g). © 2008 The College Board. All rights reserved. Visit the College Board on the Web: www.collegeboard.com. AP® CHEMISTRY 2008 SCORING GUIDELINES (Form B)
A(g) + B(g) → C(g) + D(g) For the gas-phase reaction represented above, the fo...
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- Fall '11