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3.3 Chemical Kinetics and Chemical Equilibrium 75

Table 3.2 Equilibrium constants based on partial pressure for chemical reactions
T (K) lnðK P Þ
½O 2 + ½N 2 $ NO CO 2 +H 2 $ CO 2 $ CO + ½O 2 H 2 O $ H 2 + ½ O 2
CO + H 2 O
298 −35.052 −11.554 −103.762 −92.208
500 −20.295 −4.9252 −57.616 −52.691
1,000 −9.388 −0.366 −23.529 −23.163
1,200 −7.569 0.3108 −17.871 −18.182
1,400 −6.27 0.767 −13.842 −14.609
1,600 −5.294 1.091 −10.83 −11.921
1,800 −4.536 1.328 −8.497 −9.826
2,000 −3.931 1.51 −6.635 −8.145
2,200 −3.433 1.648 −5.12 −6.768
2,400 −3.019 1.759 −3.86 −5.619
2,600 −2.671 1.847 −2.801 −4.648
2,800 −2.372 1.918 −1.894 −3.812
3,000 −2.114 1.976 −1.111 −3.086
3,200 −1.888 2.022 −0.429 −2.451
3,400 −1.69 2.061 0.169 −1.891
3,600 −1.513 0.701 −1.392
3,800 −1.356 1.176 −0.945
4,000 −1.216 1.599 −0.542

10,900 1 1
K P;NO ¼ 4:71exp for N 2 þ O 2 $ NO ð3:37Þ
T 2 2
Then the chemical equilibrium constants at different temperatures can be cal-
culated. Table 3.2 shows some examples obtained at P ¼ 1atm.

3.3.3 Chemical Equilibrium in Gaseous Combustion
Products

Now consider a general combustion reaction that converts oxygen and fuel (O and
F) into a mixture of different product gases, A, B, … Z. After chemical reactions
there are only reaction products left in the system.

oO þ fF þ ! aA þ bB þ cC þ dD þ þ yY þ zZ ð3:38Þ
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Reactant Reaction
mixutre products