Thermodynamics

Chapter 16 | 817PROBLEMS*K P and the Equilibrium Composition of Ideal Gases16–1C Why is the criterion for chemical equilibriumexpressed in terms of the Gibbs function instead of entropy?16–2C Is a wooden table in chemical equilibrium with the air?16–3C Write three different K P relations for reacting idealgasmixtures, and state when each relation should be used.16–4C1The equilibrium constant of the reaction CO 2O 2→ CO 2 at 1000 K and 1 atm is K P1. Express the equilibriumconstant of the following reactions at 1000 K in terms of K P1:(a) CO 1 2 O 2 ∆ CO 2at 3 atm(b)CO 2 ∆ CO 1 2 O 2at 1 atm(c) CO O 2 ∆ CO 2 1 2 O 2at 1 atm(d) CO 2O 2 5N 2∆ CO 2 1.5O 2 5N 2 at 4 atm(e) 2CO O 2∆ 2CO 2 at 1 atm16–5C The equilibrium constant of the dissociation reactionH 2 → 2H at 3000 K and 1 atm is K P1. Express the equilibriumconstants of the following reactions at 3000 K interms of K P1:(a) H 2∆ 2H at 2 atm(b) 2H ∆ H 2 at 1 atm(c) 2H 2∆ 4H at 1 atm(d) H 2 2N 2∆ 2H 2N 2 at 2 atm(e) 6H ∆ 3H 2 at 4 atm16–6C Consider a mixture of CO 2 , CO, and O 2 in equilibriumat a specified temperature and pressure. Now the pressureis doubled.(a)(b)Will the equilibrium constant K P change?Will the number of moles of CO 2 , CO, and O 2 change?How?16–7C Consider a mixture of NO, O 2 , and N 2 in equilibriumat a specified temperature and pressure. Now the pressureis tripled.(a)(b)Will the equilibrium constant K P change?Will the number of moles of NO, O 2 , and N 2 change?How?16–8C A reaction chamber contains a mixture of CO 2 ,CO,and O 2 in equilibrium at a specified temperature and pres-*Problems designated by a “C” are concept questions, and studentsare encouraged to answer them all. Problems designated by an “E”are in English units, and the SI users can ignore them. Problemswith a CD-EES icon are solved using EES, and complete solutionstogether with parametric studies are included on the enclosed DVD.Problems with a computer-EES icon are comprehensive in nature,and are intended to be solved with a computer, preferably using theEES software that accompanies this text.sure. How will (a) increasing the temperature at constantpressure and (b) increasing the pressure at constant temperatureaffect the number of moles of CO 2 ?16–9C A reaction chamber contains a mixture of N 2 and Nin equilibrium at a specified temperature and pressure. Howwill (a) increasing the temperature at constant pressure and(b) increasing the pressure at constant temperature affect thenumber of moles of N 2 ?16–10C A reaction chamber contains a mixture of CO 2 ,CO, and O 2 in equilibrium at a specified temperature andpressure. Now some N 2 is added to the mixture while themixture temperature and pressure are kept constant. Will thisaffect the number of moles of O 2 ? How?16–11C Which element is more likely to dissociate into itsmonatomic form at 3000 K, H 2 or N 2 ? Why?16–12 Using the Gibbs function data, determine the equilibriumconstant K P for the reaction H 2 1 2 O 2 ∆ H 2 O at(a) 298 K and (b) 2000 K. Compare your results with the K Pvalues listed in Table A–28.16–13E Using Gibbs function data, determine the equilibriumconstant K P for the reaction H 2 1 2 O 2 ∆ H 2 O at(a) 537 R and (b) 3240 R. Compare your results with theK P values listed in Table A–28. Answers: (a) 1.12 10 40 ,(b) 1.90 10 416–14 Determine the equilibrium constant K P for the processCO 2 O 2 CO 2 at (a) 298 K and (b) 2000 K. Com-1pare your results with the values for K P listed in Table A–28.16–15 Study the effect of varying the percent excessair during the steady-flow combustion ofhydrogen at a pressure of 1 atm. At what temperature will 97percent of H 2 burn into H 2 O? Assume the equilibrium mixtureconsists of H 2 O, H 2 ,O 2 , and N 2 .16–16 Determine the equilibrium constant K P for thereaction CH 4 2O 2∆ CO 2 2H 2 O at 25°C.Answer: 1.96 10 14016–17 Using the Gibbs function data, determine the equilibriumconstant K P for the dissociation process CO 2 ∆CO 1 2 O 2 at (a) 298 K and (b) 1800 K. Compare yourresults with the K P values listed in Table A–28.16–18 Using the Gibbs function data, determine the equilibriumconstant K P for the reaction H 2 O ∆ 1 2 H 2 OHat 25°C. Compare your result with the K P value listed inTable A–28.16–19 Determine the temperature at which 5 percent ofdiatomic oxygen (O 2 ) dissociates into monatomic oxygen (O)at a pressure of 3 atm. Answer: 3133 K16–20 Repeat Prob. 16–19 for a pressure of 6 atm.