Account for the enthalpy and entropy change for... #C_2H_4(g) + Cl_2(g) rarr C_2H_4Cl_2(g)# #DeltaH_"rxn"^@=-270.6*kJ*mol^-1; DeltaS_"rxn"^@=-139.0*kJ*mol^-1;# Is the reaction spontaneous at room temperature?

1 Answer
anor277
Dec 2, 2017

You gots....#C_2H_4(g) + Cl_2(g) rarr C_2H_4Cl_2(g)#

#DeltaH_"rxn"^@=-270.6*kJ*mol^-1; DeltaS_"rxn"^@=-139.0*kJ*mol^-1; #

Explanation:

The reaction is FAVOURED by enthalpy in that it is clearly thermodynamically downhill; you make strong #C-Cl# bonds, at the expense of weaker #Cl-Cl# bonds....

On the other hand, the reaction is clearly disfavoured by entropy both by the given parameters, and also there is ONE mole of gaseous product, but TWO moles of gaseous reactants. The statistical probability for disorder is clearly greater for the reactants - clearly, this is indicated by the SIGN of #DeltaS_"rxn"^@#.

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