Question

Prof. Timothy Minton of Montana State University presented a seminar on his study of atomic oxygen reaction with graphitic and vitreous carbon surfaces. He evoked the Boudouard reaction to interpret the changes of CO/CO2 time-of-flight spectra. The Boudouard reaction, 2CO(g) = CO2(g) + C(s), is said to be entropy-driven

a.) Given the standard formation of enthalpy of CO and CO2 is -110.5 and -393.5 kJ/mol and their standard entropy is 197.7 and 213.7 J/mol*K, respectively, determine the partial pressures of CO and CO2 in a container with a total pressure of 1 bar.

b.) Determine the temperature at which pCO2 = sqr(pCO)

Answer 1

2CO(g) = CO2(g) + C(s)

2CO(g) = CO2(g) + C(s)

ΔH_RXN = (SUM OF ΔH_f,PRODUCTS) - (SUM OF ΔH_{f , REACTANTS})

= -393.5 - (-110.5)= -283 KJ

ΔS_RXN = (SUM OF ΔS_f,PRODUCTS) - (SUM OF ΔS_{f , REACTANTS})

           = 213.7 - 197.7 = 16 J

ΔG = ΔH - T ΔS

TEMPERATURE IS NOT GIVEN , TAKING STANDARD TEMPERATURE AS 27^oC

ΔG = -283 - 300X16/1000 =-287.8 KJ

ΔG = -2.303RTlog(P_co2/(P_co)² )

-287.8x1000 = -2.303x8.314x300log(P_co2/(P_co)² )

log(P_co2/(P_co)² ) = 50.1

Pco₂ + Pco = 1 bar

solving above two equations we can get Individual partial pressures.