Perfect Gases :/

[Spectrum_963]

(Buckle up - I talk a lot when I'm hyped up on coffee)

So this issue has been nagging me for a while, and no one could answer me, so I'm taking it here.

We've got perfect gases right? Gases that follow every goddamn rule and are predictable. Okay. Closest thing we have to them is what? Noble gases - those with a "complete" set of electrons.

So technically, perfect gases don't exist. They're just what we think gases are approaching. No one proved they don't exist, but on the other hand, no one proved they did. (Momentarily off topic: Would they exist and not exist at the same time like Schrodinger's cat or something?)

So despite all that vagueness and unsureness, we've created formulas to predict what they'd do and how they'd act and such, even though they're just educated guesses. And we still continue researching on them, creating new formulas and ideas on something that might not even be real, teach high school kids about them and just -

Well, did anyone stop to consider that they might be wrong? That maybe a REAL perfect gas (should it exist) doesn't obey by these laws - that it's behavior turns 180 once it reaches that "perfect" state? What if all we've been studying and researching on for the last X number of years is horridly wrong? That what we think we knew about thermodynamics is false?

So why do we still continue and potentially waste more time on a good looking theory? Why not drop it and focus on what we have rather than what we think? Is there something I'm missing here?!

[HTH]

ehhhh, you're mixing Physics and Chemistry my dear

Shove the noble gases off to the side and buckle up.

We (in my field) use perfect gases as a modeling tool. We KNOW they don't exist in nature but we can get DAMN close. And it's not like we are striving to make a mystical perfect gas, toiling away in out underground laboratory... We just use certain assumptions to make dealing with real gases easier.

It's like a step up from the ideal gas law. If you are familiar with pv=nrt.. We can use ideal gas laws to model and do calculations for lots of situations, I've used them mostly in engine design...

Neither an ideal gas NOR a perfect is something we think gases are approaching like some sort of godly substance,  because they are mythical. But eliminating intermolecular forces, and assuming that thermal changes due to very slight pressure changes don't happen, and that the heat capacity is a constant if Volume is (which isnt true) all make modeling and design solutions easier.

So there is no "lab" no any money being spent... nobody is saying this is the next big step in gases.... its really just like...


If you were programming and you made a flow chart and you over simplified a few things to make your job easier until you go to actualy make it... that's what ideal and perfect gases are, they are tools. Everyone in the field/school should know that, and if someone told you otherwise... punch them in the nuts for me

PS. Anyone who wants to discuss the actual restrctions on them, etc, can feel free to PM me

Sources: Too many goddamned physics classes.

[z3ro]

Oh boy. You've got some serious shit messed up in your head.

In physics (or chemistry and many other sciences), we 'model' complex systems so that we can make predictions. These predictions might not be 100% accurate BUT they are damn well close enough for all purposes. Planets are modeled as 'perfect spheres' in many models, on a large enough scale any object, from human to a whale, are modeled as particles, etc...

So, ideal gases don't exist as of yet, so no gas obeys all these models we've created.
Why not? Cause most of these simplistic models (pV=nRT, etc) make assumptions that are not true. FOr example, intermolecular forces are neglected, collisions are modeled as elastic, ... etc...

Bottom line: Yeah. No ideal gases around. Get over it.

[Spectrum_963]

Lol yeah, they don't exist - I got that back in the ninth grade but it's not real and it doesn't apply to all gases. And some things need calculations correct down to the last decimal point.
So we've got imperfect gases that need perfect calculations and some of these formulas don't cut it. That's what I meant - sorry if it came out wrong.

[Axon]

Since these models that do not exist in the real physical world explain the physical problems with a certain degree of accuracy enough for scientists to consider them true, they are used and taught as the ideal laws unless proven otherwise.

Take the Bohr's model for example, it could not explain all the emission spectra for all the elements except Hydrogen, but it's still taught and used because it holds a degree of accuracy. The Schrodinger's equation is also an example, you can get an exact solution for the Schrodinger's equation only when you apply it to the Hydrogen atom,Why? Because it was originally derived from the Hydrogen atom, Why the Hydrogen atom? because it's the simplest atom in the periodic table (1 electron- 1 proton and 1 neutron). This is how scientists work. They hypothesize.

[z3ro]

[p_2001]

Real gases as they're called are actual `real` gases.  They exist.  Now,  ideal gases are hypothetical gases created after mathematical models.  It was always known that the mathematical model will be flawed but it is read anyways,  why? Because the actual variables for real gases are really to numerous and unless you wish to do a PHD or need some really error free data, you do not need to read it.
All real life systems can be defined with an equation of the type M + Rf ().
Where M is the mathematical model and RF () is your practical variation. 
Now,  you are taught M because you can grasp it and it doesn't need you to perform any sophisticated experiment beyond your ability to perform.  Once you are adept at it,  you're taught the practical variation that occurs.

A high school student will never need to learn the complex parts, do a PHD if you really want to learn this. 

[Architect]

It just werks.

On a serious note, the periodic table can be used to identify gases but its just that, a tool we created. Anybody outside of our gravitational pull would be like "wtf are they using to measure gases and other elements? Fucking proton count? Lol". Scientists don't know perfect mathematics when it comes to gases and other stuff that make up our universe. P_2001 is probably on the right path with his 'real' gas explanation.

[Spectrum_963]

Thanks for the help guys. Got it.