Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: mcjhn on 11/05/2011 18:10:00

Title: cloud in a bottle, why does alcohol work better than water?
Post by: mcjhn on 11/05/2011 18:10:00

Does anyone know exactly how this works?

I searched the forum and there have been some mentions of this experiment but I still have a question

Is the result entirely down to changing temperature?
expansion > cools > vapour condenses > droplets form?
compression > heats > droplets vaporise?

You can do a similar experiment just with water but I was told a cloud requires smoke particles (from a match) to act as Cloud Condensation Nuclei (same job as silver iodide in cloud making machines).
(Description of experiment here > http://www.sep.org.uk/catalyst/articles/catalyst_21_4_484.pdf)

Is it because the change in vapour pressure is greater for alcohol?

any help much appreciated

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fw3Agm.png&hash=f80af9f339249a590138951e2becde90)
graph done by geogebra

Title: Re: cloud in a bottle, why does alcohol work better than water?
Post by: lightarrow on 11/05/2011 22:42:20

I think your analysis is correct.