ap07_chemistry_form_b_sgs_final_complete

0 1007 atm 9734 10 4 atm uo2cl2g 0 9734 10 4 atm one

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Unformatted text preview: 2Cl2(g) + O2(g) ? 0 1.007 atm 9.734 × 10− 4 atm UO2Cl2(g) × 0 9.734 × 10− 4 atm ? One point is earned for the correct answer. (1 mol O 2 ) = 3.245 × 10− 4 atm O2(g) (3 mol UO 2 Cl2 ) (b) Calculate the value of the equilibrium constant, Kp , for the system at 862°C. Kp = (pUO 2Cl2 )3 ( pO 2 ) ( pCl2 )3 = (9.734 × 10−4 )3 (3.245 × 10−4 ) (1.007)3 = 2.931 × 10−13 One point is earned for the correct substitution. One point is earned for the correct answer. (c) Calculate the Gibbs free-energy change, ΔG °, for the reaction at 862°C. ΔG ° = − RT ln Kp = (−8.31 J mol−1 K−1)( (862+273) K)(ln (2.931 × 10−13)) = 272,000 J mol−1 = 272 kJ mol−1 One point is earned for the correct setup. One point is earned for the correct answer with units. © 2007 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). AP® CHEMISTRY 2007 SCORING GUIDELINES (Form B) Question 1 (continued) (d) State whether the entropy c...
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