Timeline for How to explain disagreement between Le Châtelier's principle and the simplified Gibbs free energy equation?
Current License: CC BY-SA 4.0
13 events
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| Jun 4, 2019 at 21:31 | history | edited | Buck Thorn♦ | CC BY-SA 4.0 |
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| Jun 4, 2019 at 21:00 | comment | added | Michael Lautman | @BuckThorn, this whole discussion has been very enlightening for me. I hadn't thought deeply about this topic previously. I did a major edit on my answer here in light of what you and Andrew have pointed out. | |
| Jun 4, 2019 at 17:50 | history | edited | Buck Thorn♦ | CC BY-SA 4.0 |
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| Jun 4, 2019 at 17:35 | comment | added | Buck Thorn♦ | @MichaelLautman my earlier comment "if solubility increases with increasing T I would predict that the dissolution is endothermic" was clearly wrong (in light also of my answer to a later question). This should have been "if solubility increases with increasing T I would predict that the process of formation of a saturated solution is endothermic". | |
| Jun 3, 2019 at 21:12 | comment | added | Karsten♦ | @MichaelLautman I turned your comment into a question, here: chemistry.stackexchange.com/questions/116365/… | |
| Jun 3, 2019 at 19:42 | history | edited | Buck Thorn♦ | CC BY-SA 4.0 |
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| Jun 3, 2019 at 19:04 | history | edited | Buck Thorn♦ | CC BY-SA 4.0 |
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| Jun 3, 2019 at 18:53 | comment | added | Michael Lautman | @BuckThorn Huh... I hadn't thought of it that way. You make a very valid point. That makes my initial comment seem a little silly. I still think that the OP's mistake in the qualitative Le Châtelier's analysis is the exclusion of entropy. I'm going to see if I can find some enthalpy of solution values at different temperatures. | |
| Jun 3, 2019 at 18:42 | comment | added | Michael Lautman | @BuckThorn, unfortunately that just isn't the case. As an example, LiCl. Enthalpy of solution = -37 kJ/mol. Solubility in water: 0C = 68 g/100mL, 25C = 84 g/100mL, 100C = 123 g/100mL.Source | |
| Jun 3, 2019 at 17:55 | comment | added | Michael Lautman | Does this type of analysis apply to dissolution, which is nominally a physical process. The van't Hoff equation postulates an inverse relationship between K and T for exothermic reactions. Empirically, however, we know that for the vast majority of ionic compounds, solubility increases with increasing temperature. The van't Hoff equation as written excludes entropy, which is the bit can account for the increased solubility. In these cases both the OP's Le Châtelier analysis and the use of the van't Hoff equation are incorrect. Am I wrong? | |
| Jun 3, 2019 at 17:10 | history | edited | Buck Thorn♦ | CC BY-SA 4.0 |
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| Jun 3, 2019 at 16:50 | history | edited | Buck Thorn♦ | CC BY-SA 4.0 |
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| Jun 3, 2019 at 16:06 | history | answered | Buck Thorn♦ | CC BY-SA 4.0 |