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pillanoid
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Homework Statement
Calculate the standard enthalpy change (##\Delta H##) at 25 degrees Celsius and 927 degrees Cesius for the reaction,
WCl4(g) + CH4(g) = WC(s) + 4HCl(g)
Data:
WCl4(g): ##\Delta H298## = -336 kJ/mole; Cp (heat capacity at constant pressure) = 105.6 J/mol*K
HCl(g): ##\Delta H298## = -92.3 kJ/mole; Cp = 30.5 J/mol*K
CH4(g): ##\Delta H298## = -74.8 kJ/mole; Cp = 59.1 J/mol*K
WC(s): ##\Delta H298## = -40.2 kJ/mole; Cp = 46.5 J/mole*K
Homework Equations
##\Delta H(\text{final temp}) = \Delta H(\text{initial temp}) + \Delta Cp(\text{Tf - Ti})##
##\Delta Cp = \Sigma Cp(\text{products}) - \Sigma Cp(\text{reactants})##
The Attempt at a Solution
This is a take-home test, so it doesn't feel right getting help with the actual answer, but I have some specific questions I hope can be clarified for me:
1.) When calculating ##\Delta Cp##, do you multiply each component by the number of moles involved? For instance, for the HCl factor in ##\Delta Cp##, do you multiply Cp for HCl by 4? It seems like you should, but Cp stays in the same units, so the moles wouldn't cancel.
2.) Can I apply the equation for ##\Delta H## (of reaction at 927 degrees Celsius) as I have written above (as in, is it applicable as is, or do I need to do further analysis of this specific situation as Kirchhoff's Law applies?
Thanks!
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