chapter 13 the solution process - kimika · thermodynamics – the study of heat ... the solution...
TRANSCRIPT
![Page 1: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/1.jpg)
Homework
13.115 13.122 13.130 13.133 13.139 13.143
DUE MONDAY DECEMBER 15, 2008
![Page 2: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/2.jpg)
House-keeping
Make-up Class (WHEN?!) Monday 4:30 – 6:00 PM Possibly C-114
Long test: December 17, 2008 Wednesday 4:30 – 6:00 PM or 6:00 – 7:30 PM
![Page 3: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/3.jpg)
a thermodynamic approach
![Page 4: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/4.jpg)
A few key terms
Thermodynamics – the study of heat (“energy in transit”) and its interconversion.
We talk of movement of energy in a system
![Page 5: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/5.jpg)
The solution process
Intermolecular Forces have to be broken Solute-solute Solvent-solvent
Intermolecular Forces have to be created Solute-solvent
Just like phase changes, breaking and creating forces require an input and output of energy
![Page 6: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/6.jpg)
The solution process
∆Hsol'n = ∆Hsolvent + ∆Hsolute + ∆Hmix
Breaking IMFs between solvent molecules: Endothermic, ΔHsolvent > 0
Breaking IMFs between solute molecules: Endothermic, ΔHsolute > 0
Forming IMFs between solute-solvent molecules: Exothermic, ΔHmix < 0
![Page 7: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/7.jpg)
Energy Changes
![Page 8: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/8.jpg)
Aqueous solutions salts
ΔHlattice
It is the energy needed to completely liberate ions from an ionic solid
It is endothermic!
ΔHlattice = ΔHsolute
![Page 9: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/9.jpg)
Aqueous solutions salts
ΔHhydration
Solvation (Hydration) is the process of surrounding a solute particle with solvent (water)
It is the combined process of disturbing your solvent particles and mixing solute with solvent
It is exothermic!
ΔHhydration = ΔHmix+ ΔHsolvent
![Page 10: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/10.jpg)
Aqueous solutions salts
ΔHhydration = ΔHmix+ ΔHsolvent
ΔHlattice = ΔHsolute
∆Hsol'n = ∆Hsolvent + ∆Hsolute + ∆Hmix
∆Hsol'n = ∆Hlattice + ∆Hhydration
![Page 11: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/11.jpg)
Aqueous solutions salts
![Page 12: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/12.jpg)
The solution process
Statement 1: The solution process is accompanied by heat changes (enthalpy). Exothermic processes are favored.
![Page 13: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/13.jpg)
However!
![Page 14: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/14.jpg)
Entropy
Entropy (S) is directly related to the number of ways that a system can distribute its energy.
Entropy is directly related to the freedom of motion of particles and the number of ways they can be arranged
Sgas > Sliquid > Ssolid
![Page 15: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/15.jpg)
Entropy of Solution
There are more ways you can distribute the energy in a solution than individual solute
Ssol’n > (Ssolute+Ssolvent) ∆Ssol’n> 0
![Page 16: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/16.jpg)
The solution process
Statement 1: The solution process is accompanied by heat changes (enthalpy)
Statement 2: The solution process is also accompanied by the greatest tendency to distribute energy in as many ways possible (entropy)
∆Hsol’n ∆Ssol’n
![Page 17: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/17.jpg)
So why does like dissolve like?
Case 1: NaOH in water
![Page 18: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/18.jpg)
So why does like dissolve like?
Case 2: octane in hexane
Enthalpy of solution is almost zero, the solution process is entropy driven
![Page 19: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/19.jpg)
So why does like dissolve like?
Case 3: NaCl in hexane
A solution will not form because the entropy increase is not enough to compensate for the huge enthalpy change
![Page 20: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/20.jpg)
So why does like dissolve like?
Case 4: NH4NO3 in water
The increase in entropy during crystal break down and the favorable mixing of ions in polar water solvent compensates for increase in enthalpy
![Page 21: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/21.jpg)
Thermodynamics of solution process
How is ∆G related to enthalpy (∆H) and entropy (∆S)?
For solutions to occur, ∆Gsol’n<0
∆Hsol’n ∆Ssol’n Temp
![Page 22: Chapter 13 The Solution Process - Kimika · Thermodynamics – the study of heat ... The solution process ... Chapter 13 The Solution Process.pptx](https://reader034.vdocuments.site/reader034/viewer/2022050711/5b3bc6c87f8b9a895a8cc31b/html5/thumbnails/22.jpg)
Exercise
Sketch a qualitative enthalpy diagram for the process of dissolving KCl (s) in H2O (endothermic)? NaI(s) in H2O (exothermic)?