The second part of the lecture on thermodynamics and kinetics is now available. Part 2 reviews equilibrium and speciation calculations. Equilibrium constants are reviewed and speciation models presented.
1) What is molal ionic strength? I tried looking it up and everything came back as a definition for molar ionic strength.
2) When we meet can you please explain the Cm-Humate chart on slide 2-6 in further detail. I don't quite understand what it is showing.
3) For the example using the equilibrium constants you used the approximation that 1-2x = 1. Do you want us to use that approximation with small K values since x will therefore be small? Or would you prefer that we use the method of successive approximation (or some other method) to find a more accurate value for x? Also, how do we know when K is a sufficiently small value? Or is this question even relevant since we will most likely be working with more realistic/complex environments?
4) Are stability constants and complexation constants synonymous?
molal is moles per kg solvent. So at low molality it is equivalent to molarity. At high ionic strength, the mass of that salt in the solvent becomes significant and deviations from molality occur. See: http://en.wikipedia.org/wiki/Molality
The Cm-Humate is the measured complexation constant for Cm with humic acid. The complexation constant is measured at different molal ionic strengths. The logB against the square root of the molal ionic strength is plotted. This data can be used to solve for the terms in the specific ion interaction theory.
You can solve directly if needed. This example just shows some simplifications for solving the speciation. Your last statement on relevance is important. You can use more complicated codes to solve for speciation.
Stability and complexation constants can be synonymous.
Completed.
ReplyDeleteThanks Daniel. I will assume the large file size was not a hindrance.
ReplyDeleteLecture 2, Part 2 Completed--JN
ReplyDeleteQuestions:
1) What is molal ionic strength? I tried looking it up and everything came back as a definition for molar ionic strength.
2) When we meet can you please explain the Cm-Humate chart on slide 2-6 in further detail. I don't quite understand what it is showing.
3) For the example using the equilibrium constants you used the approximation that 1-2x = 1. Do you want us to use that approximation with small K values since x will therefore be small? Or would you prefer that we use the method of successive approximation (or some other method) to find a more accurate value for x? Also, how do we know when K is a sufficiently small value? Or is this question even relevant since we will most likely be working with more realistic/complex environments?
4) Are stability constants and complexation constants synonymous?
molal is moles per kg solvent. So at low molality it is equivalent to molarity. At high ionic strength, the mass of that salt in the solvent becomes significant and deviations from molality occur. See: http://en.wikipedia.org/wiki/Molality
DeleteThe Cm-Humate is the measured complexation constant for Cm with humic acid. The complexation constant is measured at different molal ionic strengths. The logB against the square root of the molal ionic strength is plotted. This data can be used to solve for the terms in the specific ion interaction theory.
You can solve directly if needed. This example just shows some simplifications for solving the speciation. Your last statement on relevance is important. You can use more complicated codes to solve for speciation.
Stability and complexation constants can be synonymous.
JD: Lecture 2, Part 2 Completed
ReplyDeleteI completed the Thermodynamics lecture - I can see the pointer! Also, I tried to download JCHESS but the link takes you to a page that says: ERROR
ReplyDeleteThe JCHESS links work for me. Please try: http://radchem.nevada.edu/classes/rdch702/programs/chess/New%20Compressed%20(zipped)%20Folder.zip
DeleteThis link can be found at: http://radchem.nevada.edu/classes/rdch702/lectures%20and%20chapters.html
Please let me know which link did not work for you.
Thermodynamics lecture 2.2 Completed - IA
ReplyDeletethanks!
ReplyDelete