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Q & A: density of hot water

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Most recent answer: 10/22/2007
Q:
if at 4 Kelvin the densiity of water is 1000kg/m^3 and at 20 .99823km/m^3 what is density at 10^11 Kelvin? is there a constant rate? are there similar densities in the universe today?
- devon hunt (age 20)
costa mesa ca
A:
I can't tell for sure if you're kidding. 10^11 K is VERY hot. Not only would the water molecules fall apart, but so would the hydrogen and oxygen atoms. At that temperature you don't even have a fixed number of electrons, since electron-positron pairs are popping in and out of existence. At any rate, knowing the temperature isn't enough to know the density, since you'd have to know at least the pressure as well. At T= 10^11 K, it doesn't sound exactly like ordinary room conditions, so it wouldn't make sense to assume that the pressure was around one atmosphere. I can't think of anything that hot in the current universe, since the centers of stars run around 10^7 K. Maybe things get that hot in some supernova or other special object. If you want to follow up, we'll check with an astrophysicist.

Mike W.

(published on 10/22/2007)

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