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Author Topic: What is the least-viscous liquid (at room temperature) known?  (Read 47894 times)

Offline Atomic-S

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Does anyone know what is the least viscous liquid known at room temperature and pressure? And also at ANY temperature and pressure?
« Last Edit: 13/06/2010 11:27:39 by chris »


 

another_someone

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The least viscous at any temperature must be superfluid liquid helium.



George
 

Offline Atomic-S

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Ah yes; of course!
 

Offline eric l

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Viscosity is rather complex.  In fact, very few liquids behave according to Newton's law.  And if you want the "dynamic" viscoisty of the old days (viscosity over density) mercury will flow faster than water if driven by gravity alone.  I don't have the exact data here, but at room temperature the viscosity of merrcury will be lower than 2 mPa.s (water would be about 1 mPa.s) while density would be about 13,5.  Dynamic viscoity would be about 7 times lower !  And you would not need to cool to - 200C or lower as with liquified helium.
 

Offline Soul Surfer

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Ether and acetone are the liquids with the lowest viscosities at room temperature that I have seen and checking out my tables of physical constants they are the lowest viscosity common substances.
They have about the same viscosity as water near its boiling point.  At room temperature the viscosity of water is about four times this but it is still pretty runny.  The viscosity of mercury at room temperature is a bit higher than water but they are both about the same just above the freezing point of water

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« Last Edit: 29/07/2006 23:38:52 by Soul Surfer »
 

Offline eric l

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Viscosity is rather complex.  In fact, very few liquids behave according to Newton's law.  And if you want the "dynamic" viscoisty of the old days (viscosity over density) mercury will flow faster than water if driven by gravity alone.  I don't have the exact data here, but at room temperature the viscosity of merrcury will be lower than 2 mPa.s (water would be about 1 mPa.s) while density would be about 13,5.  Dynamic viscoity would be about 7 times lower !  And you would not need to cool to - 200C or lower as with liquified helium.
 

Offline Soul Surfer

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Ether and acetone are the liquids with the lowest viscosities at room temperature that I have seen and checking out my tables of physical constants they are the lowest viscosity common substances.
They have about the same viscosity as water near its boiling point.  At room temperature the viscosity of water is about four times this but it is still pretty runny.  The viscosity of mercury at room temperature is a bit higher than water but they are both about the same just above the freezing point of water

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« Last Edit: 29/07/2006 23:38:52 by Soul Surfer »
 

Offline Mjhavok

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Where do you get these physical constants tables. On the net?
 

Offline Soul Surfer

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Google  (+viscocity  +water +ether +alcohol +mercury  ) produces some lists of viscocities of common substances

I just used a table of physical constans that I have had since I was a student.

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Offline Mjhavok

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Thanks Ian.
 

Offline Atomic-S

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Acetone, you say? Well, that makes sense, come to think of it. Acetone is quite "loose" in a container.
 

Offline Bored chemist

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Have you really been waiting since August 06 for an answer? In case you have, pentane is slightly less viscous than ether.
 

Offline lightarrow

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Offline Bored chemist

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Those tables are allowed to be discordant. They are tables of different quantities.
Viscosity in poise is not the same as viscosity in stokes. There's a factor of the fluid density.
 

Offline lightarrow

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Those tables are allowed to be discordant. They are tables of different quantities.
Viscosity in poise is not the same as viscosity in stokes. There's a factor of the fluid density.
Right, thank you.
 

Offline tommya300

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A yard of grog has the least viscosity, it runs faster than all of these.  [:0]
 

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