CHEM 123 Unit 4 Test Blueprint Key

28 the water gas shift reaction plays an important

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28) The water-gas shift reaction plays an important role in the production of clean fuel from coal. CO( g ) + H 2 O( g ) CO 2 ( g ) + H 2 ( g ) After reacting for a period of time at 700K, the reaction mixture contains 0.253 atm of CO, 0.586 atm of H 2 O, 5.62 atm CO 2 and 5.62 atm H 2 . rxn rxn with temperature. Substance: CO( g ) H 2 O( g ) CO 2 ( g ) H 2 ( g ) H f (kJ/mol): -110.5 -241.8 -393.5 0 S (J/mol·K): 197.7 188.8 213.7 130.7 Is the reaction at equilibrium? If not, in which direction will the reaction proceed to reach equilibrium? (8 points) H o = 1mol(-393.5kJ/mol) [1mol(-110.5 kJ/mol) + 1mol(-241.8 kJ/mol)]
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H o = -41.2 kJ S o = 1mol(213.7 J/molK) + 1mol(130.7 J/molK) [1mol(107.7 J/molK) + 1mol(188.8 J/molK)] S o = 47.9 J/K G o = -41200 J (700K)(47.9 J/K) = -74730 J G = G o + RTlnQ G = -74730J + (8.314J/molK)(700K)ln((5.62)(5.62)/((0.253)(0.286))) G =-39353J or -39.4 kJ Since G is negative, the reaction still wants to go forward from the conditions specified to reach equilibrium. Alternatively, G o = -RTlnK -74730J = -8.314J/molK(700K)(lnK) K = 3.77 x 10 5 Q = (5.62)(5.62)/((0.253)(0.286)) = 437 Q < K so it will go forward to reach equilibrium Calculate ΔG under non -standard conditions. 29) At 2600 K, Δ G ° = 775 kJ for the vaporization of boron carbide: B 4 C( s ) → 4 B( g ) + C( s ) Find Δ G and determine if the process is spontaneous if the reaction vessel contains 4.00 mol B 4 C( s ), 0.400 mol of C( s ), and B( g ) at a partial pressure of 1.0 × 10 -5 atm at 2600 K.
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30) The equilibrium constant for the following r eaction is ΔG = -13.2 kJ at 600. K. H 2 (g) + I 2 (g) 2HI (g) a) If pressures of 5.0 x 10 -3 atm H 2 (g), 5.0 x 10 -3 atm I 2 (g) and 0.50 atm HI (g) are in the flask, what is the value of ΔG at 600. K? (5 points) G = G o + RTlnQ G = -13200J + (8.314J/molK)(600K) ln(0.50) 2 /((5.0x10 -3 )(5.0x10 -3 )) G = 32745 J or 32.7 kJ b) In which direction will the reaction proceed from the conditions in part a? Explain your reasoning. (2 points) Since G is positive, it will proceed in the reverse direction
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