Consider the conversion of water to steam at and . Find the change in Gibbs Free Energy (in ) for this reaction.
Details and Assumptions
Round off your answer to nearest integer
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To solve these kind of questions , it is better to define a energy reference level , from where all energies are to be measured.
For this particular one it will be water at 3 7 3 K
Let C p for water be C p 2 and steam be C p 1 The reaction is:
H X 2 O ( l ) → H X 2 O ( g )
We know that:
Δ G = Δ H − T Δ S
Δ H reaction = Δ H products − Δ H reactants
Δ H reaction = ( H v + Δ T C p 1 ) − ( Δ T C p 2 )
Δ H reaction = 3 9 8 9 9 . 8 6 J/mol
Now similarly:
Δ S reaction = Δ S products − Δ S reactants
Δ S reaction = ( T H v + C p 1 ln T 1 T 2 ) − ( C p 2 ln T 1 T 2 )
Δ S reaction = ( 3 7 3 4 0 6 5 7 + C p 1 ln 3 7 3 3 9 3 ) − ( C p 2 ln 3 7 3 3 9 3 )
Δ S reaction = 1 0 7 . 0 2 3
Putting values
Δ G = − 2 1 0 6 . 1 7