gas laws?????

[BiggDawg]

A High school chemistry teacher put it this way PV/MT=PV/MT Can't remember which law is which, but I do remember what happens.

That comes under the law of "Duh?!"

Either you copied that down wrong, or the teacher was unable to dazzle with brilliance so he was baffling with bu!!&4|7.

PV/MT will always equal PV/MT
just like A=A; and X=X.

 

[spectrum]

Yes, but that is not Charles' Law.

Gay-Lussac Law is worth a read regarding teperature/pressure within a fixed volume cylinder....
http://members.aol.com/profchm/gaylusac.html

Pete

 

[ClayJar]

spectrum, what that link refers to as Gay-Lussac's Law is what I'd always learned as Amonton's Law. Gay-Lussac's Law is the law of combining volumes (which should most certainly *NOT* be relevant to the gases in your scuba cylinder).

Gas Laws (Purdue)

BiggDawg: I believe what he was trying to say was "P-subscript-1 times V-subscript-1 divided by M-subscript-1 and also divided by T-subscript-1 equals P-subscript-2 times V-subscript-2 divided by M-subscript-2 and also divided by T-subscript-2".

This comes directly from the ideal gas law, PV=nRT (pressure times volume equals quantity (eg. number of moles) times the ideal gas constant times temperature). Since the ideal gas constant is... well... *constant*, you can take any set of pressure, volume, quantity, and temperature and get the same constant, assuming ideal gas behavior, which means you can set the two sets as equal. Taking it from there and cancelling out the constant terms (with respect to the problem at hand), you can simplify it to Charles', Boyle's, and Amonton's Laws (should you so desire).

 

[Blackwood]

At what depths and at what temperatures are we talking about?


Ooops I just looked back and realized I should have asked that of Blackwood.

WOW! Crazy thread resurrection.

What are you asking me? What depth/temp a tank's volume changes? It's negligable for divers. I was just having fun.

 

[miketsp]

True, but the impact Van Der Waals forces are so small, it can be neglected. PV=nRT is accurate enough for diving.

Since we're all nitpicking, I would accept that statement if you'd said recreational diving.
The Helium curve is well off PV=nRT well below 200bar and even N2 starts to distort beyond 200bar for HP tank users.

I was going to post the curves here but some days (like today) attachments just don't work, I don't know why.

 

[jbd]

WOW! Crazy thread resurrection.

What are you asking me? What depth/temp a tank's volume changes? It's negligable for divers. I was just having fun.

Glad to see you are still around. Some of these resurrected threads have participants who are no longer active on scubaboard.

 

[The Chairman]

Check out DAN's new class on inert gasses... it was covered HERE!!!

 

[miketsp]

Check out DAN's new class on inert gasses... it was covered HERE!!!

I'm missing something here. What does this post about Gas Exchange & Deco Theory have to do with the topic of this thread - basic gas laws?

 

[Scubar]

The attached link is a nice little reference.

http://www.scuba-doc.com/physics.pdf#search='diving%20physics'

 

[ClayJar]

I'm missing something here. What does this post about Gas Exchange & Deco Theory have to do with the topic of this thread - basic gas laws?

How about good ole Henry. I'd say his law is pretty basic, and it's relevant to gas exchange and deco. If they get into bubbles, you can then add Boyle to the party, and if they touch on partial pressures and mixes, that sends Dalton his invitation.