Question

Question #f4c22

Answer 1

Given

`C(gr)+O_2(g)->CO_2(g),DeltaH_1^@=-393.5" kJmol"^-1....(1)`

`CO+1/2O_2(g)->CO_2(g),DeltaH_2^@=-283.0" kJmol"^-1...(2)`

`CO+Cl_2(g)->COCl_2(g),DeltaH_3^@=-108.0" kJmol"^-1...(3)`

`"We are to determine "DeltaH_f^@" of " COCl_2(g)" for the reaction:"`

`C(gr)+1/2O_2(g)+Cl_2(g)->COCl_2(g),DeltaH_f^@=?`

It is obvious that adding(1) and (3) ,then subtracting (2) we can easily get `DeltaH_f^@` of the reaction.

So

`DeltaH_f^@=DeltaH_1^@+DeltaH_3^@-DeltaH_2^@`

`DeltaH_f^@=(-393.5-108.0-(-283.0))" kJmol"^-1`

`=-218.5kJ"mol"^-1`