Help with Thermal Conductivity - Water vs. Air

In summary, water has a higher heat conductivity than air due to its higher density and closer molecular distances, which allows for better contact with the heat source. While there may not be a direct proof, this explanation is supported by evidence and logical reasoning.
  • #1
quanchi
3
0
Help!

Which has higher heat conductivity: water or air?

And could you give me a proof as well?

Regards,
Quan Chi
 
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  • #2
quanchi said:
Which has higher heat conductivity: water or air?

Have you tried looking it up?

quanchi said:
And could you give me a proof as well?


Proof? Wouldn't this be an experimental result? Granted, it is probably possible for someone to use theoretical physics arguments to predict what the heat conductivity of a substance depends upon and therefore which one would be higher. But that would be a lot of work and would seem to be unecessary if you just want the answer.

EDIT: Unless somebody has asked YOU to provide such a derivation, in which case asking somebody else to do it for you is cheating.
 
  • #3
Just an answer would be enough. I have tried looking it up without success so I thought I might just ask some professional help. I have no time to do a research and english is not my native language.
And the reason I am asking this question is a quarrel I had with my friends. I thought the correct answer was water but I could not prove it to them so easily.
 
  • #5
Thank you very much :)
 
  • #6
Just to throw a wrench in the works, the data is not corrected for density. For example, there are two ways to quantify viscosity- kinematic and dynamic- water and air have about the same dynamic viscosities.

The Prandtl number (ratio of viscous to thermal diffusion) does take this into account, and is about 0.7 for air and 7 for water.
 
  • #7
If I were to explain why water is a better thermal conductor than air, I would say because liquid are denser than air (molecular distances are small) thus giving water more opportunity to contact with the heat source.

There are rarely proofs in physics theories, if any. But explanation like those can be taken as self-evident. And in some other cases, we can only feel confident about an explanation because it's grounded on suggestive evidence and logic that's been rigorously examined.
 
Last edited:

1. How does thermal conductivity differ between water and air?

Thermal conductivity is a measure of how well a material can transfer heat. Water has a higher thermal conductivity compared to air, meaning it can transfer heat more efficiently. This is because water molecules are more tightly packed and have stronger intermolecular forces, allowing heat to be transferred more easily.

2. Why is water a better conductor of heat than air?

Water has a higher thermal conductivity due to its molecular structure. Its molecules are closer together and have stronger bonds, making it easier for heat to be transferred between them. In contrast, air molecules are more spread out and have weaker bonds, resulting in a lower thermal conductivity.

3. How does thermal conductivity affect the rate of heat transfer?

The higher the thermal conductivity of a material, the faster heat can be transferred through it. This means that water can transfer heat more quickly than air. In everyday situations, this can be seen when boiling water heats up food faster than hot air in an oven.

4. Does the temperature of water or air affect their thermal conductivity?

Yes, the temperature of a substance can affect its thermal conductivity. Generally, as the temperature increases, so does the thermal conductivity. This means that hot water will have a higher thermal conductivity than cold water, and the same applies to air.

5. How do other factors, such as pressure and density, influence the thermal conductivity of water and air?

Pressure and density can also affect the thermal conductivity of water and air. In general, as pressure and density increase, so does the thermal conductivity. This is because higher pressure and density result in closer molecule spacing and stronger intermolecular forces, making it easier for heat to be transferred. However, the effect of pressure and density on thermal conductivity is not as significant as the effect of temperature.

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