Textbook Problem 4B. 5

[kirsten clemente 1E]

Hi!

I worked out this problem according to the student manual, but I am having trouble understanding why we would put 750/760 as the Pext.

Wouldnt Pext just be 750? since it was given that way? I'm not sure I fully understand thermodynamics just yet. Does anyone have any other resources that helped them grasp this concept? (Other than lecture, discussion, and UA sessions)

[Truman Ma 3I]

Yes you are right that 750 torr is the pressure. However, you divide by 760 to convert the torr to atm, which works with the gas constant we use.

[Janice Shin 1G]

Since the pressure is 750 Torr, we want to convert Torr to units of atm so that we can convert the product of our calculation, 1.48 L atm, to Joules.

0.08206 Late/Kmol = 8.314 JK/mol

[Emma MacLachlan 1D]

Like others have stated, the Pressure external is 750 torr. If you use this value to calculate work, then work will be given in torr. Therefore, you need to convert torr to atm. Likewise, for the change in volume which is given in the problem to be ml should be converted to L so that work is given in atm L. This is because there is a constant which converts L atm to J which is the unit of work that we want.