Chapter 16 | 817KPand the Equilibrium Composition of Ideal Gases
16–1C Why is the criterion for chemical equilibrium
expressed 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 KPrelations for reacting ideal-
gas mixtures, and state when each relation should be used.
16–4C The equilibrium constant of the reaction CO
→CO 2 at 1000 K and 1 atm is. Express the equilibrium
constant of the following reactions at 1000 K in terms of :
(a) at 3 atm
(b) at 1 atm
(c) at 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 atm
16–5C The equilibrium constant of the dissociation reac-
tion H 2 →2H at 3000 K and 1 atm is. Express the equi-
librium constants of the following reactions at 3000 K in
terms of :
(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 atm
16–6C Consider a mixture of CO 2 , CO, and O 2 in equilib-
rium at a specified temperature and pressure. Now the pres-
sure is doubled.
(a) Will the equilibrium constant KPchange?
(b) 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 equilib-
rium at a specified temperature and pressure. Now the pres-
sure is tripled.
(a) Will the equilibrium constant KPchange?
(b) 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-∆∆∆∆∆KP 1KP 1∆∆COO 2 ∆CO 2 ^12 O 2CO 2 ∆CO^12 O 2CO^12 O 2 ∆CO 2KP 1KP 11
2 O 2sure. How will (a) increasing the temperature at constant
pressure and (b) increasing the pressure at constant tempera-
ture affect the number of moles of CO 2?
16–9C A reaction chamber contains a mixture of N 2 and N
in equilibrium at a specified temperature and pressure. How
will (a) increasing the temperature at constant pressure and
(b) increasing the pressure at constant temperature affect the
number 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 and
pressure. Now some N 2 is added to the mixture while the
mixture temperature and pressure are kept constant. Will this
affect the number of moles of O 2? How?
16–11C Which element is more likely to dissociate into its
monatomic form at 3000 K, H 2 or N 2? Why?
16–12 Using the Gibbs function data, determine the equi-
librium constant KPfor the reaction at
(a) 298 K and (b) 2000 K. Compare your results with the KP
values listed in Table A–28.
16–13E Using Gibbs function data, determine the equilib-
rium constant KP for the reaction at
(a) 537 R and (b) 3240 R. Compare your results with the
KPvalues listed in Table A–28. Answers:(a) 1.12 1040 ,
(b) 1.90 104
16–14 Determine the equilibrium constant KPfor the pro-
cess CO O 2 CO 2 at (a) 298 K and (b) 2000 K. Com-
pare your results with the values for KPlisted in Table A–28.
16–15 Study the effect of varying the percent excess
air during the steady-flow combustion of
hydrogen at a pressure of 1 atm. At what temperature will 97
percent of H 2 burn into H 2 O? Assume the equilibrium mix-
ture consists of H 2 O, H 2 ,O 2 , and N 2.
16–16 Determine the equilibrium constant KP for the
reaction CH 4 2O 2 CO 2 2H 2 O at 25°C.
Answer:1.96 10140
16–17 Using the Gibbs function data, determine the equi-
librium constant KPfor the dissociation process
at (a) 298 K and (b) 1800 K. Compare your
results with the KPvalues listed in Table A–28.
16–18 Using the Gibbs function data, determine the equi-
librium constant KPfor the reaction
at 25°C. Compare your result with the KPvalue listed in
Table A–28.
16–19 Determine the temperature at which 5 percent of
diatomic oxygen (O 2 ) dissociates into monatomic oxygen (O)
at a pressure of 3 atm. Answer:3133 K
16–20 Repeat Prob. 16–19 for a pressure of 6 atm.H 2 O∆^12 H 2 OHCO^12 O 2CO 2 ∆∆1
2H 2 ^12 O 2 ∆H 2 OH 2 ^12 O 2 ∆H 2 OPROBLEMS**Problems designated by a “C” are concept questions, and students
are encouraged to answer them all. Problems designated by an “E”
are in English units, and the SI users can ignore them. Problems
with a CD-EES icon are solved using EES, and complete solutions
together 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 the
EES software that accompanies this text.cen84959_ch16.qxd 5/11/05 10:08 AM Page 817