## H2 co2 h2o co

Its equilibrium constant K, expressed as molar concentrations, is a function of temperature.

The five equations above have six unknowns: namely, the five molar concentrations and K, which is a function of temperature. Solving for nn2 and K:

K can be obtained from a table of the water-gas reaction as a function of temperature. Try T = 2500 K and K = 6.440 and substitute above.

«H,O = 1-500 -«h, =0.836 nC02 = 0.164 «co =0.836

The heats of formation Ay-//0 for the various species are listed in the table below [from the JANAF thermochemical tables (Refs. 5-7 and 5-9)]. The heat of reaction is obtained from Eq. 5-9 in kilojoules per mole. By definition, the heat of formation of H2 or N2 is zero. From Eq. 5-9,

= 0.836(—241.8) + 0.164(—393.5) + 0.836(-l 10.5) - 1.0(-113.1) = —246kJ/mol

The enthalpy change of the gases going from the reference conditions to the combustion temperature can also be obtained from tables in Refs. 5-7 and 5-8 and is again listed below.

 Species AfH° Ah?00 Molecular Weight "j n2 