What happens to pressure when a liquid turns into a gas in a confined chamber?

I'm doing an experiment requiring immense pressures. Since I do not have access to a pump that can create these pressures I settled on something different...

Instead of using a pump I want to utilize the expansion ratio from liquid to gas of a particular element; liquid Neon. Neon has the highest expansion ratio of all known substances, by a factor of 1:1445!

I was wondering, if I put liquid Neon in a container with a given volume, seal it, and then heat it above Neon's boiling point (not very hard as Neon's boiling point is 27.104 K) what would happen to the pressure once the Neon has expanded by a factor of 1:1445? How much liquid Neon would I need to achieve a certain pressure with a container of a given volume? Would the increased pressures have any effect on the boiling point of the Neon?

I'm assuming the ideal gas laws apply, but if they don't let me know!

• ideal gas laws do not apply when the density of the gas is approximately the same as the density of its liquid form. You need a more complicated relationship called an equation of state for that substance, which applies where the ideal gas law does not. All equations of state are approximations that work well in certain ranges of temperature and pressure, so care has to be applied when choosing which one to use.. – niels nielsen Mar 23 at 19:25
• BTW if you are working with pressures that great, what sort of container do you intend to use for confining the neon? – niels nielsen Mar 23 at 19:26
• I don't know about "expansion ratio," but if your plan is to pressurize a vessel by sealing a liquified substance inside, then the the most relevant property of the substance probably would be its vapor pressure – Solomon Slow Mar 23 at 19:27
• last comment: you should be able to find something called a phase diagram for neon on the web, which tells you how neon behaves at a variety of different pressures and temperatures. Do you have one in hand? – niels nielsen Mar 23 at 19:28
• Re, "...once the Neon has expanded by a factor of 1:1445?..." OK, Wikipedia says that expansion ratio is the ratio of volume of some amount of cryogenic liquid at amospheric pressure, and the volume of the same amount of gaseous substance at room temperature and at amospheric pressure. If your goal is to achieve "immense pressure," then it's not going to expand all that much. – Solomon Slow Mar 23 at 19:36

The gas would not expand 1445 times unless you use a small amount in a large vessel. If it is a sealed vessel, the pressure would increase until it reached max pressure of the vessel or it reached equilibrium.

I work with anhydrous ammonia on a regular basis. I will talk about the pressure and temperature of ammonia as it is what I am most familiar with.

One of the worst things you can do is trap liquid ammonia in a pipe.
-28F it would be at 0 psi 0F - 16 psi

32F - 48 psi

60F - 93 psi

100F - 200 psi

With ammonia, you only fill a tank part of the way to allow the gas to flash and stabilize.

To do your experiment, you are going to need safety relief valves, a lot of specialized equipment. What you are proposing is very dangerous.

Your vessel has to be rated for 40% more pressure than you expect to achieve. Unless you are using very small amounts, this is not something you can piece together yourself. You are going to need a way to fill the vessel, and then remove the liquid when you are done. You are going to need a way to add the neon without heating it up too much.

Boiling point is a function of pressure.

As the pressure goes up, so does the boiling point (for most materials)

You should find a phase diagram for neon, and look at the line between gas and liquid. That will tell you what temperature you need to reach your desired pressure.

• "Boiling point is a few nation of pressure." That sentence really doesn't rock... – Gert Mar 23 at 21:28
• Sorry, I plead autocorrect. Thanks for pointing it out. – Bob Jacobsen Mar 23 at 21:29