1. I'm currently studying for my IGCSE is physics and my syllabus often oversimplifies things, so they no longer make any sense.

In my textbook it states that: "As a gas is cooled (if kept at a constant volume), the pressure keeps decreasing. However, the pressure of a gas cannot become less that zero. The temperature in which the gas cannot be cooled anymore is known as absolute zero (-273 degrees Celcius)"
I would imagine that at these tempertures, gases would freeze, yet my textbook implies that the gases never freeze.
Is this a misunderstanding on my part? Or has the textbook oversimplified?

Thanks

2.

3. High temperature in a gas makes the molecules shake alot and creates a certain amount of pressure, as the temperature lowers, less energy is put into the molecules which causes that they shake less, and collide less, which causes that the pressure drops. At a certain temperature (0 Kelvin = -273,15 °C) the temperature can't be lower anymore, and there is no energy putt in the molecules which causes that they doesn't shake anymore and doesn't collide, and so their isn't any pressure anymore. However, nobody achieved to drop the temperature of a gas lower than -273°C so it is pretty much impossible to reach the absolute zero.
It is possible to keep a gas from freezing as the pressure is kept low.
I hope you understand as my engish is pretty bad, search for 'phase transition' on wikipedia, it shoud help you alot!

4. I've understood that absolute zero is at best a concept, since atoms are always vibrating. I this interesting article below, which defined absolute zero is:

Absolute zero corresponds to the theoretical state in which particles have no energy at all, and higher temperatures correspond to higher average energies.
Perhaps a physicist can give you a more thorough explanation.

Quantum gas goes below absolute zero

5. does helium ever reach a solid state?
Or is superfluid the end of the line?

6. At normal pressure, helium remains a fluid down to absolute zero. Solid helium requires a temperature of 1–1.5 K (about −272 °C or −457 °F) and about 25 bar (2.5 MPa) of pressure.

7. thanks

8. As present definitions go, absolute zero means that there is no energy within a system/ physical volume/ atom/ molecule(s). There have been claims of lower "temperatures" than absolute zero. Whether this is true or not is partly based upon definitions. If temperatures were possible below absolute zero then such a volume would always draw energy from its environment, as any temperature would if its surrounding environment were at a higher temperature. Here is an explanation of it.

A temperature below absolute zero

9. Originally Posted by forrest noble
As present definitions go, absolute zero means that there is no energy within a system/ physical volume/ atom/ molecule(s).
Sigh. True to form, Forrest, you mangle the definition. Can you PLEASE refrain from providing answers when you don't know what you're talking about? If you can't, then at least cut-and-paste from an authoritative source. Stop relying on pop-sci press articles. But it would be best if you merely stopped answering until you actually learn the material. You create extra work for those of us who care enough to mop up after you make a mess.

Absolute zero is formally defined as the temperature at which the change in entropy -- not energy -- goes to zero, so that the entropy is a minimum. There remains at that temperature the zero-point energy. Given how many times you've blathered incessantly about ZPE, it's somewhat of a surprise that you understand it so poorly that you fail to mention it in your "answer" here. But only somewhat.

10. Originally Posted by tk421
Originally Posted by forrest noble
As present definitions go, absolute zero means that there is no energy within a system/ physical volume/ atom/ molecule(s).

Absolute zero is formally defined as the temperature at which entropy -- not energy -- goes to zero. There remains at that temperature the zero-point energy. .
I'm rusty on all this but just a quibble: if Entropy is Q/T, then isn't it a bit tautologous to define absolute zero as the temperature at which entropy goes to zero?

11. Originally Posted by exchemist
Originally Posted by tk421
Originally Posted by forrest noble
As present definitions go, absolute zero means that there is no energy within a system/ physical volume/ atom/ molecule(s).

Absolute zero is formally defined as the temperature at which entropy -- not energy -- goes to zero. There remains at that temperature the zero-point energy. .
I'm rusty on all this but just a quibble: if Entropy is Q/T, then isn't it a bit tautologous to define absolute zero as the temperature at which entropy goes to zero?
You're not a bit rusty at all! In my haste, I omitted an all-important delta. I've corrected my post to read "change in entropy." Thanks for your eagle eyes!

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