Pressure and Heat - the relation

[des-esseintes]

I'm not perfectly sure if this is the right forum, but I put it here because there is no "general physics" forum. Oh well...

The state of a mass can be altered by changing either heat or pressure. Heat any solid and it becomes liquid, then gas, then plasma. Increased pressure, on the other hand, makes a mass "harder" (for instance liquid oxygen in tanks)

1) In space there is no pressure. But not all matter in space is plasma. Or is it? Why/why not?

2) What kind of pressure would it take to create a pure hydrogen cube of 1 ccm at 0 degrees C. Put the answer in elephants please :D

I am very very uneducated, enlighten me! :-)

[swansont]

I'm not perfectly sure if this is the right forum, but I put it here because there is no "general physics" forum. Oh well...

The state of a mass can be altered by changing either heat or pressure. Heat any solid and it becomes liquid, then gas, then plasma. Increased pressure, on the other hand, makes a mass "harder" (for instance liquid oxygen in tanks)

1) In space there is no pressure. But not all matter in space is plasma. Or is it? Why/why not?

2) What kind of pressure would it take to create a pure hydrogen cube of 1 ccm at 0 degrees C. Put the answer in elephants please :D

I am very very uneducated, enlighten me! :-)

To create a plasma you need to ionize the atoms, and this requires energy. Atoms in outer space aren't typically subjected to any energy source that would tend to ionize them. Atoms that are heated will reach a point that they will be continually ionized - the thermal energy exceeds the ionization energy - so that you have a plasma.

Solid hydrogen has been formed, but I'm only aware of results at liquid helium temperatures - about 4K. But you're free to use PV=nRT and try to extrapolate those results (I recommend Google to search for 'solid hydrogen' info)

[BPHgravity]

2) Answer: I'm going to take a wild stab at this and say 42 elephants. ;)

[Crash]

African elephants?

[des-esseintes]

42 elephants, let's see... that is about 160 tons. Then there must be a 10-cm-thick layer of hard hydrogen at the bottom of the Atlantic :D

To create a plasma you need to ionize the atoms, and this requires energy. Atoms in outer space aren't typically subjected to any energy source that would tend to ionize them. Atoms that are heated will reach a point that they will be continually ionized - the thermal energy exceeds the ionization energy - so that you have a plasma.

I am stupid, but do you need energy in the same way to create gas?

[Tesseract]

African elephants?

I dont understand why des wanted it in elephants???as for comparison? :confused:

[swansont]

do you need energy in the same way to create gas?

Depends on the gas. Some atoms or molecules are gases at room temperature and pressure. Some need to be heated. Depends on the boiling point.

(Technically, everything has a vapor pressure, so you will find some gas of even a metal at room temperature - but it's a very, very small amount compared to the other constituents.)