Water: A Conductor or Insulator?

Thread Starter

mavchick43

Joined Oct 15, 2012
1
Hello All,

I am confused as to why pure water is considered a poor conductor (insulator) of heat while dirty water is considered a good conductor of heat. Can someone please provide an explanation?

Thank you.
:)
 

Wendy

Joined Mar 24, 2008
22,141
The answer is in ionization. When something is ionized, it is usually short electrons, and so becomes a conductor. Ultra pure water, also known as DI (deionized) water is an insulator. Add a little table salt and the conductance (ability to carry current) increases dramatically.

Gases heated until they are glowing are also ionized (such as reentering space vehicles), the glowing air is very conductive indeed.
 

WBahn

Joined Mar 31, 2012
25,745
While Bill was talking about electrical conductivity, there is a general correlation between things that are good (or bad) electrical conductors and things that are good (or bad) thermal conductors and for the same reasons. But this is not universal and there are examples, such as diamond, where a very good electrical insulator is also a very good thermal conductor. This is because there are multiple ways for materials to conduct both electricity and heat and while some of them overlap, not all of them do.
 

HonT

Joined Oct 25, 2012
14
Hello All,

I am confused as to why pure water is considered a poor conductor (insulator) of heat while dirty water is considered a good conductor of heat. Can someone please provide an explanation?

Thank you.
:)
Can you describe what you mean by "dirty"? What exactly is the composition of the "dirty" water?
 

Wendy

Joined Mar 24, 2008
22,141
Whatever is in it. It is not clean. Since it is a solvent, it is by definition usually ionized.

This one is a no brainer, so why the question?
 
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