A 275-mL flask contains pure helium at a pressure of 752 torr. A
...

Question

A 275-mL flask contains pure helium at a pressure of 752 torr. A
second flask with a volume of 475 mL contains pure argon at a
pressure of 722 torr. If we connect the two flasks through a stopcock
and we open the stopcock, what is the partial pressure of
argon?

Accepted Answer

Hey there, welcome back. Alright, so at 25 degrees Celsius, we have a one liter vessel that is filled with 2.30 g of argon. So we have a sample of methane vapor that was introduced into that same vessel until the total pressure reached 1.6 20 atmospheres. So we have two different questions determine the partial pressure of argon and then determine the partial pressure of methane. Alright, so first we're gonna go ahead and take a look at obviously a and in order to find the partial pressure of argon, we are going to utilize the ideal gas law equation. Uh Let's take a look at that. We have PV equals NRT. And the partial pressure of this gas of argon is just p pressure. Right? So if we sell for pressure, we divide both sides by volume, which is N. R. T. Over V. This is the equation we're going to use to find the partial pressure of argon because and here is moles. We don't have moles but we we can figure out from the from the massive organ that's given to us are we always have because it's a constant T. Is temperature. Um and Celsius, we just need to go ahead and convert that into Calvin by adding to 73.15 to that because remember when we are dealing with ideal gasses temperature has to be in Calvin's. So that will give us 2 98.15 Calvin. Okay, the volume we have is one liter vessel. Okay, and the volume obviously is not changing here. So let's go ahead and plug stuff in. But first before we do that, we actually do need to find moles of Oregon. So we have 2.30 grams of argon. We just need to uh no, it's that's not A G. It's a Are we just need to know its molar mass in order to convert. So in one mole Of Argon, if you take a look at the periodic table, find organ. It weighs about 40 g Per one. Right? So here g cancel out. And that will give us . 75 moles of argon. Right? So that is the mold that we put into here. That's that's in. Okay, so now we're ready to find P and the speed. This pressure will be the partial pressure of argon because we're only using molds of argon and not the total moles. Right? Soapy here is going to equal to Moles which is .05 Times are ours. Our gas constant. It is .08 Leaders times atmospheres over more times Calvin. And then-t temperature. We just figured out that it is to 98.15 in Calvin. And then the volume here is just one leader. So the leader is the correct unit that we need. So pressure here, let's see if we can figure out, we can cancel out the molds with moles Calvin's with Calvin's leader with leader and then we're going to have atmosphere left over and that is the unit that we want because we're solving for P which is pressure. Okay, So go ahead and multiply the top numbers and of course divided by one and that will give us 1.407. And of course in atmospheres and that is the partial pressure of Oregon. Alright, so that is the answer to question A to the first question. Now you're wondering are we going to have to do the same thing with methane? Well, no, because we can't even do that because we actually do not know how many moles or how many grams of methane. We we have it just has a sample of methane. So for me it's gonna be way way easier because we have the partial pressure of organ and we have the total pressure which is 1.620 atmospheres. There's nothing else in that vessel is just argon and everything. So if we subtract the partial pressure of argon from the total, that will give us the rest which would be of methane. Okay, so that that's pretty easy. So pressure of methane oops of methane is going to equal to the Total pressure which is 1. minus the pressure of the argon. Okay, and that will be 0. Atmospheres. Right? So that's the pressure of of a thing. Very simple. Right? Alright folks. So we're all done. I hope you're able to follow along If you have any questions, of course, let us know, and we'll see you in the next video.

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