Help with measuring the amount of air you would breathe

[GinaTy05]

I'm supposed to be conducting an experiment for my chemistry class. Here is the task:

The gas laws are used to determine the pressure of compressed air in a scuba tank. This project will require you to make some basic measurements necessary to calculate the amount of air required to remain underwater for a given time. You will devise a method for measuring the amount of air you would breathe in 30 minutes. Then, using the appropriate gas law, you will calculate the final pressure of a scuba tank holding that much air.

Any help would be much appreciated! Please email me at RTyquiengco@aol.com or reply back on here. Thank you.

 

[Quarrior]

do a google search on dive planning and air consumption

 

[H2Andy]

i see three setps to your problem:

1. how much air do you breathe at the surface in 30 minutes. (easy: you
measure how much air you breathe in five minutes and multiply by 6, for example;
an easy way of doing this is to start with a small pony bottle, figure out how much
air you start with, then how much you end up with, and substract)

2. at any given depth, how much faster would you consume that air (and thus how much more air would you need to remain there for 30 minutes)?

3. for the various depths, what would the pressure of the air in the tank be? (i assume in psi, but could be bar).

hope that helps... you should be able to do the rest from your knowledge of gas laws.

 

[Uncle Pug]

You would need to know:
1. The amount of air you use at the surface.
2. The depth at which you would be breathing from the scuba tank.
3. The initial pressure of the scuba tank.
4. The capacity of the scuba tank.

Make it easy on yourself and assume these values for the above:
1. .5 cubic feet per minute
2. 33' sea water (which equals 1 atmosphere)
3. 3000 psi
4. 80 cubic feet when filled to 3000 psi

Need help stringing this together for the answer?

 

[H2Andy]

Pug, i think she's supposed to actually measure the amount of air she breathes
at the surface. sounds like a hands-on type thing.

Gina, what grade is this for?

 

[Uncle Pug]

I always look for the easy way. I guess the part about *devise a method for measuring the amount of air you would breath* requires an addition to the list of assumptions.
1. I would breath from a scuba tank at the suface for 6 minutes, note the pressure drop and multiply by 5.
2. I am assuming that my depth would be 33' which is 1 atmosphere... which is an increase in ambient pressure of 100% thus doubling the answer in step 1. (here is where you use the gas law)
3. I would assume that I started with a full tank at 3000 psi and so my final pressure would be 3000 minus the answer from step 2.

Actually, eliminating the conversion between volume and pressure makes it even easier. No access to a scuba tank is needed. Just make the assumption that you used 600 psi at the surface.

 

[The Kraken]

Well, on one of those days that it's just too crappy to go diving, if there is such a thing, go rent a tank, bring it home, set up your regulator sit down on the sofa, turn on the football game and see how long it take you to breathe the tank down.

Now don't forget to write the time down when you started breathing from the tank.

When you run out of air, divide the amount of air that was in the tank by the number of minutes you breathed before you ran out of air.

This will give you your surface air consumption in cubic feet per minute.

 

[GinaTy05]

i see three setps to your problem:

1. how much air do you breathe at the surface in 30 minutes. (easy: you
measure how much air you breathe in five minutes and multiply by 6, for example;
an easy way of doing this is to start with a small pony bottle, figure out how much
air you start with, then how much you end up with, and substract)

2. at any given depth, how much faster would you consume that air (and thus how much more air would you need to remain there for 30 minutes)?

3. for the various depths, what would the pressure of the air in the tank be? (i assume in psi, but could be bar).

hope that helps... you should be able to do the rest from your knowledge of gas laws.

Thank you. I think that the bottle method would be perfect.

 

[GinaTy05]

You would need to know:
1. The amount of air you use at the surface.
2. The depth at which you would be breathing from the scuba tank.
3. The initial pressure of the scuba tank.
4. The capacity of the scuba tank.

Make it easy on yourself and assume these values for the above:
1. .5 cubic feet per minute
2. 33' sea water (which equals 1 atmosphere)
3. 3000 psi
4. 80 cubic feet when filled to 3000 psi

Need help stringing this together for the answer?

LOL, yes, I will need some help.

 

[GinaTy05]

Pug, i think she's supposed to actually measure the amount of air she breathes
at the surface. sounds like a hands-on type thing.

Gina, what grade is this for?

This is a grade for my chemistry class. This project is basically takes up the whole grading period so I have to do well on it if I want to pass.