Van der Waals Equation Example 1

by Jules Bruno
Was this helpful ?
here. The example Question states using the Vander Waals equation determine the pressure of g oxygen gas in 250 ml graduated flask when the temperature is 50 degrees Celsius. Alright, So we're going to say the Vander Waals equation is pressure plus n squared times, a over V squared times volume minus end times B equals and are cheap. Now all we gotta do is plug in the values that we have. So we need to have the moles off oxygen. Remember, oxygen is diatonic. So one mole of 02 ways 32 g, though, too. So when we do that, we're gonna get our moles of 02 comes out as 20.6 to 5 moles of 02 volume has to be in leader. So that's 0.250 leaders and then temperature needs to be in Kelvin. So at 2 73 15, that gives us 3 23 points. 15 Kelvin. Since we're dealing with 02 in the charts up above, we would see that the a constant it comes out to 1. The B constant comes out 2. with this information, we plug it into the formula. All right, so let's see, we're looking for pressure, so we don't know it. So this is gonna be 0.6 to 5 squared times 1.360 divided by volume squared, which is 0.250 squared. And this is gonna be times volume, which is 0.250 minus moles, which is 0.6 to 5 times 0.318 And this is gonna equal. My moles are and t so, moles we wanna actually move all this out of the way. So we have space to write this out. So here are moles again. Come out to 0.6 to 5. So the Vander Waals equation related to the ideal gas law so are again is 0.8 to 06 and then temperatures 23 15 Kelvin, When I multiply these three together on this side, it comes out to be see, we're gonna multiply those out together. That comes out to be 16. 356 When I when I do this value minus these two multiplying, what I get is I'm going to get 0. Then when I work all of this out in here, this comes out to be 8. plus p. So now I need to isolate my P. So I'm gonna divide both sides here by 0. So plea P plus eight five equals 72.0 Subtract 85 from both sides. So P equals 63. atmospheres. So that would be the pressure of 02 when utilizing the Vander Wal's equation.