Timeline for What is the difference between melting and dissolving?
Current License: CC BY-SA 3.0
10 events
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| May 12, 2012 at 22:07 | comment | added | Janice DelMar | @Juha I'll work on summarizing my answer tonight. In your comment above you ask "if you want to demonstrate this, which materials you would use and why?" Can you be a bit more specific about what you're thinking there? A system where your can tell the difference and a system where you can't tell the difference? A system where you know for sure? I'll incorporate that answer into the summary. | |
| May 12, 2012 at 22:03 | comment | added | Janice DelMar | @Juha Melting and dissolving give a similar macroscopic result in some cases (if the two liquids are miscible) but on a microscopic level they are quite different (as F'x noted in his original comment to you). I don't think that most chemists (thinking on a microscopic level) would agree that they are "so similar that they cannot be separated from each other". It would be easy to tell, even if two liquids looked the same, whether you had a mixture (dissolved material) or a single substance that melted, and this difference would affect all of their chemical and physical properties. | |
| May 12, 2012 at 19:35 | comment | added | Juha | Could you add some kind of summary to the beginning of your answer? See my answer below what I mean. I really don't want to accept my own answer. | |
| May 12, 2012 at 16:50 | vote | accept | Juha | ||
| May 12, 2012 at 19:31 | |||||
| May 12, 2012 at 16:34 | comment | added | Juha | So, can I say that melting and dissolving are so similar in some cases that they cannot be separated from each other? And if you would want to demonstrate this, which materials you would use and why? (I can ask this in another thread if this becomes too broad for this) | |
| May 11, 2012 at 21:15 | comment | added | Janice DelMar | Rereading your comment more carefully: If you were near the melting point of the solid and the two liquids mixed, it would be difficult (impossible?) to tell and could be a mixture of both. (If the liquids were immiscible, then you could watch the solid melt as a separate layer.) If you were at a temperature much lower than the melting point of the solid, and it went into solution, then it dissolved. | |
| May 11, 2012 at 15:52 | comment | added | Janice DelMar | @Juha..So, perhaps the distinction is whether or not there is a solvent present with a bit of "are you above the solids melting point" thrown in. Sugar dissolves in water at room temperature, even if you hold that temperature constant...it doesn't melt. So, if I'm understanding you, your second equation was asking if ice (solid water) would dissolve in ethanol (mp -114) at something like -50 degrees C? | |
| May 11, 2012 at 15:44 | comment | added | Janice DelMar | @Juha: www.thefreedictionary.com/dissolvedis·solve (d -z lv ). v. dis·solved, dis·solv·ing, dis·solves. v.tr. 1. To cause to pass into solution: dissolve salt in water. 2. To reduce (solid matter) to liquid form; melt. | |
| May 11, 2012 at 11:56 | comment | added | Juha | If I make some summary: In both cases there is an Energy barrier that you have to break. In melting, only one exothermic reaction is known. To me the processes look very similar. If you have two exothermic reactions, one where a solid material X melts in a liquid Y into mixture of liquids X and Y and a second where solid material X dissolves into liquid Y forming a solution of X and Y. How can you tell did it melt or dissolve? Is it just that the reaction components are different (mixture of liquids vs. solution)? | |
| May 10, 2012 at 21:00 | history | answered | Janice DelMar | CC BY-SA 3.0 |