Eli5: My head hurts from watching so many youtube videos about gas laws etc and I still dont understand what partial pressure means.

Question

Can someone please explain to me the definition of partial pressure in a very simple simple way and how it applies to us?

Like the partial pressures of different gases in our bodies.. And why people get decompression sickness when they scuba dive.. And why having helium lessens the risk. Etc. Why are partial pressures important?

TIA!!

In: 3

Answer 1

Okay, say you have a room with 3 gases in it.

Say the total pressure is 100 PSI.

Each of those gasses are contributing to that total pressure based on how many molecules of each gas is present.

So it could be that one gas, say nitrogen, is contributing 70 PSI out of the total 100PSI, so it has a partial pressure of 70psi.

Another gas could be oxygen, it contributing a pressure of 20 psi out of the total PSI, so it has a partial pressure of 20psi

And the third gas could be helium, contributing 10 PSI out of the total 100PSI, having a partial pressure of 10 psi.

70+20+10=100

Another way to think about it is imagine you had a perfectly sealed container, again with three gases. Let’s use the same example gases as above.

Your sealed container is at 100 psi, if you were able to remove all the oxygen out of it perfectly without taking the other two gases, the pressure in the container would now be 80psi. Because all the pressure from the oxygen is gone since you took the oxygen out.