Answer for PART A and PART B
Entropy and the Second Law of Thermodynamics
According to the second law of thermodynamics, all reactionsproceed spontaneously in the direction that increases totalentropy. The total entropy is defined as
%u0394Stotal=%u0394Ssystem+%u0394Ssurroundings
The direction of a spontaneous change is always determined bythe sign of the total entropy change:
-The reaction is spontaneous if %u0394Stotal>0.
-The reaction is nonspontaneous if %u0394Stotal<0.
-The reaction is at equilibrium if %u0394Stotal=0.
The value of %u0394Stotal depends on %u0394Ssystem and%u0394Ssurroundings, which are defined by%u0394Ssystem=S(products)%u2212S(reactants) and%u0394Ssurroundings= %u2212%u0394Hsystem/T
Spontaneity is therefore affected by the enthalpy of the systemand the Kelvin temperature.
********PartA CaO can be used as a drying agent. One suchapplication occurs when water is added to dry concrete or cement.The reaction that occurs isCaO(s)+H2O(l)%u21CCCa(OH)2(s)
The product is commonly called slaked lime.Assuming the commonly used standard-state temperature of25%u2218C,calculate %u0394Stotal for this reaction using tablefrom the table below.
Substance S%u2218
[J/(K%u22C5mol)] %u0394H%u2218f
(kJ/mol) CaO(s) 39.9 %u2212635.1 H2O(l) 69.9 %u2212285.8 Ca(OH)2(s) 83.4 %u2212986.1
Express your answer to threesignificant figures and include the appropriate units.
*********PartB A particular solvent with %u0394S%u2218vap=112.9J/(K%u22C5mol) and %u0394H%u2218vap=38.0kJ/mol is being consideredfor an experiment. In the experiment, which is to be run at 75%u2218C, the solvent must not boil. Basedon the total entropy change associated with the vaporizationreaction, would this solvent be suitable and why or why not? The solvent wouldA particular solvent with and is being considered for anexperiment. In the experiment, which is to be run at 75 , thesolvent must not boil. Based on the total entropy change associatedwith the vaporization reaction, would this solvent be suitable andwhy or why not? be suitable because %u0394Stotal>0. not be suitable because %u0394Stotal>0. be suitable because %u0394Stotal<0. not be suitable because %u0394Stotal<0.
Answer for PART A and PART B
Entropy and the Second Law of Thermodynamics
According to the second law of thermodynamics, all reactionsproceed spontaneously in the direction that increases totalentropy. The total entropy is defined as
%u0394Stotal=%u0394Ssystem+%u0394Ssurroundings
The direction of a spontaneous change is always determined bythe sign of the total entropy change:
-The reaction is spontaneous if %u0394Stotal>0.
-The reaction is nonspontaneous if %u0394Stotal<0.
-The reaction is at equilibrium if %u0394Stotal=0.
The value of %u0394Stotal depends on %u0394Ssystem and%u0394Ssurroundings, which are defined by%u0394Ssystem=S(products)%u2212S(reactants) and%u0394Ssurroundings= %u2212%u0394Hsystem/T
Spontaneity is therefore affected by the enthalpy of the systemand the Kelvin temperature.
CaO(s)+H2O(l)%u21CCCa(OH)2(s)
The product is commonly called slaked lime.Assuming the commonly used standard-state temperature of25%u2218C,calculate %u0394Stotal for this reaction using tablefrom the table below.
| Substance | S%u2218 [J/(K%u22C5mol)] | %u0394H%u2218f (kJ/mol) |
| CaO(s) | 39.9 | %u2212635.1 |
| H2O(l) | 69.9 | %u2212285.8 |
| Ca(OH)2(s) | 83.4 | %u2212986.1 |
| be suitable because %u0394Stotal>0. | |
| not be suitable because %u0394Stotal>0. | |
| be suitable because %u0394Stotal<0. | |
| not be suitable because %u0394Stotal<0. |
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