I found this data table and in density row, the information seems wrong to me. The problem is that some of these fluorocarbons are in gas form while others are in liquid form at the temperature that is connected to the density number.

There are six fluorocarbons, first two have density specified at 20 degree Celsius, while other four have it at 25 degree Celsius. If we compare the boiling points to the temperatures at which the density was specified, we would see that first two fluorocarbons would be in gas form, while later four in liquid form.

Going from gas to liquid creates large density changes yet these substances seems to have density numbers suggesting that the first two fluorocarbons are in liquid form which is weird and unexpected in my opinion as their boiling points and density temperature specs suggest that at the temperature at which density was measured, they should clearly be in gas state.

Is that error by author of that table or do I not know something that would help me understand it?

  • 1
    $\begingroup$ It is not temperature alone that defines whether a substance will be in gas or liquid state. $\endgroup$ – Ivan Neretin Mar 7 '18 at 21:52
  • $\begingroup$ Its also atmospheric pressure,since it wasnt mentioned at what pressure is that density supposed to exist,I assume its 1 atm,in that case the numbers are wrong.Even if the pressure was different than 1 atm,then its still wrong,some will be gas,others liquid,just the boiling points will be shifted... The only way for it to make sense is if the pressure and gravity force values were different for each substance.That would be crazy to measure one thing on mars,other at moon,one at 1 atm,other at 1000 atm and not mention it, $\endgroup$ – wav scientist Mar 7 '18 at 22:54
  • 1
    $\begingroup$ Review your assumptions. You have boiling points at 1 atm, this is said quite explicitly. But it is not specified at what pressure the densities were measured. $\endgroup$ – Ivan Neretin Mar 7 '18 at 23:02
  • 3
    $\begingroup$ Ever saw a cheap cigarette lighter made of transparent plastic? Remember that liquid inside? Its density is very real, relevant, palpable. And yet it is a gas liquefied by pressure, and the pressure required is not all that high - it is nowhere near a thousand atm, not even a hundred. Same thing with your perfluorocarbons. Helium can't be liquefied by pressure alone, but they can. As for making educational webpages, this activity is not licensed, hence technically any kind of person (including crazy person) might be able to do that. $\endgroup$ – Ivan Neretin Mar 8 '18 at 0:01
  • 1
    $\begingroup$ Vapor is a gas. $\endgroup$ – Ivan Neretin Mar 8 '18 at 12:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.