2 N(g) N2 (g) Using the table of average bond energies below, determine the enthalpy change, for the ΔH, reaction. Bond Average Bond Energy (kJ mol-1) N N 160 – N = N 420 N N 950 ≡ b. The reaction between nitrogen and hydrogen to form ammonia is represented below. N2(g) + 3 H2(g) 2 NH3(g) = - 92.2 kJ ΔHo Predict the sign of the standard entropy change, for the reaction. Justify your answer. ΔSo, c. The of for the reaction represented in part (b) is negative at low temperatures but ΔGo positive at high temperatures. Explain. d. When N2(g) and H2(g) are placed in a sealed container at a low temperature, no measurable amount of NH3(g) is produced. Explain. 2011 B#3 Answer the following questions glucose, C6H12O6, an important biochemical energy source. a. Write the empirical formula of glucose. In many organisms, glucose is oxidized to carbon dioxide and as represented by the following equation. C6H12O6(s) + 6 O2(g) 6 CO2(g) + 6 H2O(l) A 2.50 g sample of glucose and an excess of O2(g) were placed in a calorimeter. After the reaction was initiated and proceeded to completion, the total heat released by the reaction was calculated to be 39.0 kJ. b. Calculate the value of in kJ mol-1, for the combustion of glucose. ΔHo, c. When oxygen is not available, glucose can be oxidized by fermentation. In that process, ethanol and carbon dioxide are produced, as represented by the following equation. C6H12O6(s) 2 C2H5OH(l) + 2 CO2(g) = -68.0 kJ mol-1 at 298 K ΔHo The value of the equilibrium constant, for the reaction at 298 K is 8.9 × 1039. KP, i.) Calculate the value of the standard free energy change, for the reaction at 298 K. ΔGo, Include units with your answer. ii.) Calculate the value of the standard entropy change, in J K-1 mol-1, for the reaction ΔSo, at 298 K.
2 N(g) N2 (g) Using the table of average bond energies below, determine the enthalpy change, ΔH, for the reaction. Bond Average Bond Energy (kJ mol-1) N – N 160 N = N 420 N ≡ N 950 b. The reaction between nitrogen and hydrogen to form ammonia is represented below. N2(g) + 3 H2(g) 2 NH3(g) ΔHo = - 92.2 kJ Predict the sign of the standard entropy change, ΔSo, for the reaction. Justify your answer. c. The of ΔGo for the reaction represented in part (b) is negative at low temperatures but positive at high temperatures. Explain. d. When N2(g) and H2(g) are placed in a sealed container at a low temperature, no measurable amount of NH3(g) is produced. Explain. 2011 B#3 Answer the following questions glucose, C6H12O6, an important biochemical energy source. a. Write the empirical formula of glucose. In many organisms, glucose is oxidized to carbon dioxide and as represented by the following equation. C6H12O6(s) + 6 O2(g) 6 CO2(g) + 6 H2O(l) A 2.50 g sample of glucose and an excess of O2(g) were placed in a calorimeter. After the reaction was initiated and proceeded to completion, the total heat released by the reaction was calculated to be 39.0 kJ. b. Calculate the value of ΔHo, in kJ mol-1, for the combustion of glucose. c. When oxygen is not available, glucose can be oxidized by fermentation. In that process, ethanol and carbon dioxide are produced, as represented by the following equation. C6H12O6(s) 2 C2H5OH(l) + 2 CO2(g) ΔHo = -68.0 kJ mol-1 at 298 K The value of the equilibrium constant, KP, for the reaction at 298 K is 8.9 × 1039. i.) Calculate the value of the standard free energy change, ΔGo, for the reaction at 298 K. Include units with your answer. ii.) Calculate the value of the standard entropy change, ΔSo, in J K-1 mol-1, for the reaction at 298 K.
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