Van’t Hoff equation and equilibrium concentration

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Van’t Hoff equation and equilibrium concentration

Post by pliz89 »


I got this assignment.

Normal air (0.78% N2, 0.21% O2) is held at 2000K long enough to reach chemical
equilibrium with NO and NO2. Assume that the only reactions involving NO and NO2 are:
1) N2 + O2 - 2NO
2) NO + 0.5O2 - NO2

The equilibrium constants obtained at 300K for the formation of NO and NO2 are:

for 1) Keq:7 x 10^-31
for 2) Keq: 1.4 x 10^6

The standard heats of formation at 25ºC are:
HfºN2 = 0, HfºO2 = 0, HfºNO = 90.25 kJ/mol, HfºNO2 =33.2 kJ/mol

Please, could you help me about:

point.a) Using Van’t Hoff equation, Calculate the concentrations of all components when equilibrium is reached at 2000K

point.b) Plot the calculated equilibrium concentration of NO at two different oxygen contents of the reacting gas. Case 1 :78% nitrogen, 21% oxygen; and case 2: 78% nitrogen, 4% oxygen in a temperature range between 300 and 4000K

Thank you
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