ch09 - CHAPTER NINE 9.1 4 NH 3 (g) + 5O 2 (g) 4NO(g) + 6H 2...

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CHAPTER NINE 9.1 9.2 a. b. c. d. e. f. a. b. c. 45 904 7 3 NH g O g) 4NO(g) + 6H O(g) kJ / mol 22 r o () ( ± . +→ =− H When 4 g-moles of NH 3 (g) and 5 g-moles of O 2 (g) at 25 ° C and 1 atm react to form 4 g-moles of NO(g) and 6 g-moles of water vapor at 25 ° C and 1 atm, the change in enthalpy is -904.7 kJ. Exothermic at 25 ° C. The reactor must be cooled to keep the temperature constant. The temperature would increase under adiabatic conditions. The energy required to break the molecular bonds of the reactants is less than the energy released when the product bonds are formed. 2 5 2 3 NH g O g) 2NO(g) + 3H O(g) ( Reducing the stoichiometric coefficients of a reaction by half reduces the heat of reaction by half. ± . . H r o kJ / mol 904 7 2 452 4 NO(g) + 3 2 HO (g ) NH g O g ) →+ 3 5 4 ( Reversing the reaction reverses the sign of the heat of reaction. Also reducing the stoichiometric coefficients to one-fourth reduces the heat of reaction to one-fourth. ± (. ) . H r o kJ / mol =+ 904 7 4 226 2 ² ² . ²² ² ± . . m g / s n 340 g 1 mol s 17.03 g mol/s QH = nH 20.0 mol NH kJ s4 m o l N H NH NH NH r o NH 3 3 3 3 3 3 = == × 340 200 904 7 452 10 4 ν kJ / s The reactor pressure is low enough to have a negligible effect on enthalpy. Yes. Pure water can only exist as vapor at 1 atm above 100 ° C, but in a mixture of gases, it can exist as vapor at lower temperatures. C H l O g) 9CO (g) +10H O(l) kJ / mol 92 2 r o 20 14 6124 ( ± H 2 When 1 g-mole of C 9 H 20 (l) and 14 g-moles of O 2 (g) at 25 ° C and 1 atm react to form 9 g-moles of CO 2 (g) and 10 g-moles of water vapor at 25 ° C and 1 atm, the change in enthalpy is -6124 kJ. Exothermic at 25 ° C. The reactor must be cooled to keep the temperature constant. The temperature would increase under adiabatic conditions. The energy required to break the molecular bonds of the reactants is less than the energy released when the product bonds are formed. ² ± . = 25.0 mol C H 6124 kJ 1 kW s 1 mol C H 1 kJ / s kW CH r 0 0 0 0 0 × 153 5 9- 1
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9.2 (cont'd) d. e. Heat Output = 1.53 × 10 5 kW. The reactor pressure is low enough to have a negligible effect on enthalpy. C H g O g) 9CO (g) +10H O(l) (1) kJ / mol C H l O g) 9CO (g) +10H O(l) (2) kJ / mol (2) C H l C H g C H C) kJ / mol kJ / mol) = 47 kJ / mol 92 2 2 r o 2 2 r o 99 v o 9 20 20 20 20 20 14 6171 14 6124 1 25 6124 6171 () ( ± ( ± ( ) ± (, ( +→ =− −⇒ −− H H H D Yes. Pure n-nonane can only exist as vapor at 1 atm above 150.6 ° C, but in a mixture of gases, it can exist as a vapor at lower temperatures. 9.3 9.4 a. b. c. a. b. Exothermic. The reactor will have to be cooled to keep the temperature constant. The temperature would increase under adiabatic conditions. The energy required to break the reactant bonds is less than the energy released when the product bonds are formed. CH g O g CO g HOg l HOl B tulb-mo l e 61 4 2 r o 4 2 r o bg bg bg b g +→+ = = = × 19 2 67 1 19 2 67 2 1 7 9 1 1 0 22 2 6 ∆∆ ± ?
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ch09 - CHAPTER NINE 9.1 4 NH 3 (g) + 5O 2 (g) 4NO(g) + 6H 2...

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