Do ionic compounds such as NaCl become individual ions such as one Na ion and one Cl ion or are they hold together by ionic bonds even when they are boiled. Thanks in advance.

  • $\begingroup$ See: chemistry.stackexchange.com/questions/2511/… $\endgroup$ – theorist Apr 21 '19 at 1:55
  • $\begingroup$ Ah! The question isn't clear .. By the way , how can you boil NaCl !! Until and unless you melt and then boil it to vaporize it... $\endgroup$ – Sreetama ghosh hazra Apr 21 '19 at 2:39
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    $\begingroup$ Some of the most celebrated experiments in Chemistry have been done on NaI molecules in the vapour phase by Zewail and coworkers. They observed that the dissociation of NaI molecules into Na + I atoms takes place in steps as the molecule vibrates. Zewail was awarded the Nobel Prize for these experiments. $\endgroup$ – porphyrin Apr 21 '19 at 8:20
  • $\begingroup$ @porphyrin, Zewail must be using very powerful lasers. $\endgroup$ – M. Farooq Apr 21 '19 at 15:51
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    $\begingroup$ Zewail did not use very powerful ones in that sense but ones that produce very short pulses typically $10^{-13} seconds long. Such pulses are actually not that herd to produce in the lab and are produced in a laser oscillator by the process called mode-locking. $\endgroup$ – porphyrin Apr 22 '19 at 10:14

Interesting question with no generic answer. Boiling the salts, or ionic compounds, makes them a plasma or freely moving ions is nothing but a misconception. The temperature is too low to convert a substance into a plasma.

  1. Let us start with ionic liquids which are room temperature cations and anions but made up of organic molecules. You heat them, to the state of boiling in the absence of oxygen. They decompose into various products. So nothing special, this is as expected for organic compounds.

  2. Heating of non-decomposable salts at high temperatures, for example, NaCl, KCl: What will happen when we heat them to the point of boiling? Answer is nothing. They remain in vapor phase as NaCl "molecules". The vapors behave as gases. People have developed equations of state. Interestingly enough $\ce{Na2Cl2}$ (dimers) are found in gas phase.

See: Critical point and vapor pressure of ionic fluids including NaCl and KCl, Chemical Physics Letters, 105, 1984, 484-489

  1. Ionic materials, KCl or NaCl, when introduced into flames or plasma convert into gas phase "atoms". For example $\ce{Na+}$ would be converted into a neutral Na atom. This is utilized in a completely different field in chemistry, called flame atomic absorption or flame atomic absorption spectroscopy.

In short, these complexities make science very interesting.

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  • $\begingroup$ The user have asked about ' boiling ' , heating and boiling are completely two different terms . Isn't? $\endgroup$ – Sreetama ghosh hazra Apr 21 '19 at 4:31
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    $\begingroup$ To be precise, it is heating to the point of boiling. Note vaporization occurs even before boiling, just like water. There is nothing special in heating, melting and vaporization of ionic salts. $\endgroup$ – M. Farooq Apr 21 '19 at 4:38
  • $\begingroup$ Boiling is the rapid vaporization of a liquid, NaCl in aqueous phase can only be boiled.. or it can be melted and then can be boiled to the state of vaporization $\endgroup$ – Sreetama ghosh hazra Apr 21 '19 at 4:45
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    $\begingroup$ I think you misunderstood the question. The poster is asking about "solid" NaCl which has been heated above its melting point (>800 oC) and heating is continued to the extent that liquid NaCl becomes a vapor. There is no discussion of water anywhere. $\endgroup$ – M. Farooq Apr 21 '19 at 4:49
  • $\begingroup$ Hold on , points you are stating haven't been stated in the poster .. mere assumptions.. question is itself unclear $\endgroup$ – Sreetama ghosh hazra Apr 21 '19 at 4:57

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