Carbon monoxide, base enthalpy

Carbon monoxide is a colorless, odorless, flammable, almost insoluble, very toxic gas that condenses to a colorless liquid at — 90°C. It is not very reactive, largely because its bond enthalpy (1074 kj-mol-1) is higher than that of any other molecule. However, it is a Lewis base, and the lone pair on the carbon atom forms covalent bonds with J-block atoms and ions. Carbon monoxide is also a Lewis acid, because its empty antibonding Tr-orbitals can accept electron density from a... 

The extent of thermal dissociation of phosgene at 0.5, 1.0 and 10 bar pressure (0.05, 0.1 and 1 MPa, respectively) has been calculated [1764] based on the accepted ideal gas thermodynamic values [359aa], and is illustrated in Fig. 5.3, whilst the enthalpy of formation for this reaction has been based on actual measurements of the equilibrium constant in the temperature range of 645-725 K by heating together carbon monoxide and dichlorine [218], see Section 6.1. The equilibrium reaction depicted in Equation (5.1) has been measured experimentally both by dissociation of phosgene and by association of carbon monoxide and dichlorine [216]. At 603, 553 and 503 C, the dissociation was found to be 91, 80 and 67%, respectively, in reasonable agreement with the values based on the ideal gas calculations illustrated in Fig. 5.3. At temperatures above 800 C, the dissociation is essentially complete [216]. 

Determine the equilibrium composition that is achieved at 300 bar and 700 K when the initial mole ratio of hydrogen to carbon monoxide is 2. You may use standard enthalpy and Gibbs free energy of formation data. For purposes of this problem you should not neglect the variation of the standard heat of reaction with temperature. You may assume ideal solution behavior but not ideal gas behavior. You may also use a generalized fugacity coefficient chart based on the principle of corresponding states as well as the heat capacity data listed below. 

Look closely at Figure 1.6. This diagram is a model for a reaction that takes place in two distinct steps. If we plot the reactions based on their relative energy, you can see the relationship among the values obtained for the enthalpy of formation of carbon monoxide. The formation of CO2 is plotted at a level corresponding to -393.5 kj/mol. The diagram shows the reverse of the combustion reaction (+283.0 kJ/mol) is added to that level. From the diagram, you see the difference between the two. This represents the formation of CO. The value of this is —110.5 kj/mol. 

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