Timeline for Why is there any vapor above the water surface at atmospheric pressure and room temperature?
Current License: CC BY-SA 4.0
9 events
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| Jan 6, 2020 at 6:23 | comment | added | theorist | @Chris: The OP wrote: "I introduce some of this special gas between the water surface and the piston and still maintain 1 ATM pressure." As that language would normally be interpreted, he's referring to the total pressure, not the partial pressure of the special gas. Thus it's not the case that "by construction, the special gas always has a partial pressure of 1 atm and a total pressure of 1 atm". | |
| Jan 1, 2020 at 11:16 | comment | added | Borun Chowdhury | @BobJacobsen the comment immediately above is for you as well but I can only notify one person so made another comment for you. | |
| Jan 1, 2020 at 11:16 | comment | added | Borun Chowdhury | So @Chris you guys are saying (and if so then I agree) that applying a pressure of 1 ATM by a piston directly and via the 'special gas that does not dissolve in water' are two different things. In the first case at 50 C and 1 ATM there will be no vapor and in the second there will be. Fine but in the second case how much water will convert into vapor? What is the criteria for finding that? I keep hearing/reading partial pressure of water vapor will be equal to the vapor pressure at 50 C. But why is that the case (assuming that's the answer you were gonna give)? | |
| Dec 31, 2019 at 22:20 | comment | added | Chris♦ | @BorunChowdhury Basically what Bob says. There is no such special gas- any real gas will mix into the water to some degree, and vice-versa. | |
| Dec 31, 2019 at 22:11 | history | edited | Chris♦ | CC BY-SA 4.0 |
added 62 characters in body
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| Dec 31, 2019 at 21:53 | comment | added | Bob Jacobsen | There is no “special gas” that can exclude other molecules. | |
| Dec 31, 2019 at 21:32 | comment | added | Borun Chowdhury | See the answer by Bob Jacobson. I am basically arguing along the lines of your argument and his and cannot make up my mind. | |
| Dec 31, 2019 at 21:27 | comment | added | Borun Chowdhury | That's what I was thinking but all I assumed was that the special gas does not dissolve in water. Is it sufficient to show that water vapor will not evaporate and mix into the gas as well? I'd rather see a proof of this using Free energies than hand wave but if I get a good argument I can try to make a formal one. | |
| Dec 31, 2019 at 20:31 | history | answered | Chris♦ | CC BY-SA 4.0 |