Periodic Table
T-Shirts & more
from the
meta-synthesis



Merch Store

previous home next

Thermochemistry: Play With Reaction Synthlet


    
   or    Kelvin        
Decomposing steam into its elements
    2 2       +        
Steam
 
Reactants
  
Hydrogen
 +
Oxygen
 
Products
  
Products – Reactants
ΔfH⦵
  
 
Σf-reactH⦵
  
ΔfH⦵
  
ΔfH
 
 
Σf-prodH⦵
  
Σf-prodH⦵ - Σf-reactH⦵ = ΔrH⦵
(-241.8 x 2)
=
-483.64
 
(0.0 x 2)
+
(0.0 x 1)
=
0.0
 
0.0 - -483.6 = 483.6 kJmol-1
                             
S⦵
  
 
ΣreactS⦵
  
S⦵
  
S
 
 
ΣprodS⦵
  
ΣprodS⦵ - ΣreactS⦵ = ΔrS⦵
(0.189 x 2)
=
0.378
 
(0.131 x 2)
+
(0.205 x 1)
=
0.467
 
0.467 - 0.378 = 0.089 kJK-1mol-1
Gibbs free energy at 298K (standard conditions and standard temperature):
  
ΔrG⦵   = ΔrH⦵ – (T298 x ΔrS⦵)   =   483.6– (298 x 0.089)  =
+457.2kJmol-1
ΔrH⦵
=
 +483.6 kJmol-1 Positive value: the reaction is endothermic
ΔrS⦵
=
 +0.089 kJK-1mol-1 Positive value: the system becomes more dispersed
ΔrG⦵ 298K
=
 +457.2 kJmol-1 Positive value: the reaction is not feasible (spontaneous)
Keq 298K
=
 7.38 x 10-81 Value is less than 1: the reaction proceeds to the left
ΔG° = 0.0, and the system is at equilibrium, at a temperature of 5,444K (5,171°C)
previous home next
List Thermochemical Reactions Build-a-Reaction Synthlet

© Mark R. Leach 1999 –

Queries, Suggestions, Bugs, Errors, Typos...

If you have any:

Queries
Comments
Suggestions
Suggestions for links
Bug, typo or grammatical error reports about this page,

please contact Mark R. Leach, the author, using mark@meta-synthesis.com

This free, open access web book is an ongoing project and your input is appreciated.