If you want to use the Ideal Gas law to calculate the number of moles of Butane in a graduated cylinder which is filled with water submerged in a basin of water and you dispense butane underwater into the graduated cylinder. Which partial pressure equation would I use? (2 formulas below)

Question

tpaulus · Answer

$$P _{but}=P_{ambient}-P_{Vapor Pressure of Water}$$
$$P _{but}=P_{ambient}-P_{Vapor Pressure of Water}$$

anonymous · Answer

did you copy the same equation twice?

tpaulus · Answer

Oops, one should have a plus sign.$$P _{but}=P_{ambient}+P_{Vapor Pressure of Water}$$

anonymous · Answer

I believe it would be the one with the plus sign due to the fact that you have water and butane inside the cylinder.

tpaulus · Answer

Okay, that's what my dad said too, but the one with the minus sign was on our instructions that we got from our teacher and was giving me extremely high error.