Sublimation (chemistry)
Please post your comments and suggestions for this article.
Comment by Domingo Morales on December 5th, 2012 at 12:33 pm
I saw your article at http://www.newworldencyclopedia.org/entry/Sublimation_(chemistry)
I think sublimation is a physics phenomenon, not a chemical one.
I am right?
Thank you,
Domingo Morales
BTW, I was looking for a long list of substances that undergo sublimation, but also specifically C2H2 ethyne acetylene.
Comment by Domingo Morales on December 5th, 2012 at 12:36 pm
sorry, muy email address is dmorales21@yahoo.com
Domingo Morales
acethylene???
Comment by Domingo Morales on December 5th, 2012 at 12:46 pm
Yep, everything, from top to bottom, in the article “Sublimation (chemistry)” at http://www.newworldencyclopedia.org/entry/Sublimation_(chemistry) deals with physics (change of state, not change of nature). Sometimes a word like “physicalchemistry” maybe used, but I would not think of “chemistry”.
Domingo Morales
Comment by Dinshaw Dadachanji on December 5th, 2012 at 6:49 pm
Hello Domingo,
Sublimation refers to a process by which a chemical substance goes from a solid phase (or solid state) directly to the gas phase, without becoming a liquid. During sublimation, the chemical nature of the substance does not change. In that sense, it is called a physical change, not a chemical one. However, because sublimation is a property of chemical substances, it is usually studied as a part of chemistry.
In the case of acetylene, when the pressure is the same as atmospheric pressure, acetylene sublimes (goes from solid to gas) at -84°C. To obtain liquid acetylene, the pressure needs to be at least 1.27 atmospheres. Thus, sublimation of a solid chemical depends on the pressure of its surroundings (or the pressure within the container in which the chemical is kept.)
Hope this helps.
Sincerely,
Dinshaw Dadachanji
Science Editor
Comment by Dinshaw Dadachanji on December 6th, 2012 at 11:19 am
Domingo,
In response to your comment of Dec. 5, 2012, at 12:46 pm, I’d like to add the following:
The science of chemistry is not restricted to chemical changes of substances. It includes physical changes as well, such as the phase changes that occur when heating or cooling different substances or mixtures. In a practical chemistry setting, the chemist needs to know the physical properties as well as the chemical properties of the materials being used. Sublimation is just one type of physical property that chemists need to be aware of. Melting and boiling are other examples of physical properties that chemists commonly deal with.
Dinshaw Dadachanji
Science Editor
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