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List Thermochemical Reactions Build-a-Reaction Synthlet

Thermochemistry: Play With Reaction Synthlet


    
   or    Kelvin        
Water-steam equilibrium
    
Water
 
Reactants
 
Steam
 
Products
 
Products – Reactants
Δf H ⦵
 
 
Σf-react H ⦵
 
Δf H ⦵
 
 
 
Σf-prod H ⦵
 
Σf-prod H ⦵ - Σf-react H ⦵ = Δr H ⦵
(-285.8 x 1)
=
-285.83
 
(-241.8 x 1)
=
-241.8
 
-241.8 - -285.8 = 44.0 kJmol-1
                             
S ⦵
 
 
Σreact S ⦵
 
S ⦵
 
 
 
Σprod S ⦵
 
Σprod S ⦵ - Σreact S ⦵ = Δr S ⦵
(0.070 x 1)
=
0.070
 
(0.189 x 1)
=
0.189
 
0.189 - 0.070 = 0.119 kJK-1mol-1
Gibbs free energy at 298K (standard conditions and standard temperature):
 
Δr G ⦵   = Δr H ⦵ – (T 298 x Δr S ⦵)   =   44.0– (298 x0.119)  =
+8.6kJmol-1
Δr H ⦵
=
 +44.0 kJmol-1 Positive value: the reaction is endothermic
Δr S ⦵
=
 +0.119 kJK-1mol-1 Positive value: the system becomes more dispersed
Δr G ⦵ 298K
=
 +8.6 kJmol-1 Positive value: the reaction is not feasible (spontaneous)
K eq 298K
=
 0.0314 Value is less than 1: the reaction proceeds to the left
ΔG° = 0.0, and the system is at equilibrium, at a temperature of 370K (97°C)
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List Thermochemical Reactions Build-a-Reaction Synthlet

© Mark R. Leach 1999 –

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