Studying for nitrox class- please help

[dannobee]

If we're at 66 ft and diving 21%, we're at 3atm.

If we're diving air (21%) our partial pressure of oxygen is 0.63 (3 x 0.21) and our partial pressure of nitrogen is 2.37 (3 x 0.79).

If we're on 32% our partial pressure is 0.96 (3 x 0.32) and our partial pressure of nitrogen is 2.04 (3 x 0.68).

 

[pacificgal]

It does, thank you parz

 

[parzdiver]

It does, thank you parz

It helps to turn intangible or unfamiliar things (minutes, air) into tangibles (pints of good ice cream).

 

[pacificgal]

Maybe I'll get a lesson on Henry's Law tomorrow?

By the time I get to class Wednesday I should have them all down.
I do need to say on my behalf, however, college was a long time ago, I never took physics, and I know how to safely plan my gas for the dives I am doing, I'm just not using physics to do so, I'm using my experience and know approximately how long my gas is going to last for the dive I plan on doing, and know that I'll ascend with about 300 psi more than my buddy.

 

[akscubainst]

Funny thing about this Nitrox class, a) It's not PADI--therefore I'm not expecting it to be easy

Funny thing is that the question you asked about is on the PADI OPENWATER class final exam......

 

[deadly_risk]

Here are some instructional videos explaining some of the concepts behind your practice question.
Chemistry : Chapter 8 : Tutorials

A more interactive demonstration (remember, the volume in this example is different from what you use in scuba, but ignore it, the concepts are the same)
http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/boyles_law.swf

Here is another animation this time with narration on what is happening.
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/gasesv6.swf


These might help, if you find them just confusing you either ask questions or ignore them completely. No use toiling in uncertainty and confusion.

 

[imwright1985]

Funny thing is that the question you asked about is on the PADI OPENWATER class final exam......

yeah i believe it is on padi's final and i think the last review or next to last review. wouldnt it be 2 atm, unless your in a physics class then you would take a progressive atmospheric pressure increase where it would come up to like 2.78atms

 

[DNCkevin]

Hey!! "and know that I'll ascend with about 300 psi more than my buddy" I know that we only dove once together but I don't think your statement is always true.

 

[pacificgal]

I'm talking about my regular buddy, not every buddy

 

[pacificgal]

Seriously though, you dive with someone a lot, you know what size tank they are carrying, you know what their psi is when they get into the water, you ask every 10 mins. what their SPG says, you compare it to yours, by the 3rd time you ask you can almost guess how much air will be in their tank by comparing it to yours.
Though in reality, maybe you don't even need to ask. You set a turnaround pressure and a rock bottom psi when you do your dive planning, then you only have to do two signals, turn around and ascend.