PE Practice Exams & other reference materials

[dagget]

I dont understand how you got the mols of N2 and moles of O2 equations? Maybe im just having an incredible brain fart right now, but its incredibly frustrating.

From stoichiometry....and the fact that, for ideal gases, mol fraction is equal to volume fraction.

In Eq (1) each mole of NO that is created requires the destruction of 0.5 mole of N2, so we subtract 0.5x from the total starting N2 amount of 0.79. Similarly, using the re-formed eq (2) in the box, each mole of NO2 requires 0.5 mole of N2.

Same for oxygen, 0.5 mole for each mol of NO and a full mol for each mol of NO2.

 

[rppearso]

Help with Question 2 on the 6 min solutions problems, I struggle a bit with partial pressures and I have no idea where they get the equation for this problem in the solutions. Thank you

 

[dagget]

Help with Question 2 on the 6 min solutions problems, I struggle a bit with partial pressures and I have no idea where they get the equation for this problem in the solutions. Thank you

Here's what I did with number 2. The equation in the solutions appears to be something they made up to do multiple steps at once. Not something that I try to do.

Meanwhile, can someone explain attachment management to me. I had to zip this page as there wasn't space to uploaded it raw, but I don't see any way to free up space. Thanks.

 

[rppearso]

Here's what I did with number 2. The equation in the solutions appears to be something they made up to do multiple steps at once. Not something that I try to do.
Meanwhile, can someone explain attachment management to me. I had to zip this page as there wasn't space to uploaded it raw, but I don't see any way to free up space. Thanks.

Hello Dagget,

I have been working through and am noticing the 6 min solutions questions are not very easy and take me way longer than 6 min to solve if I can even solve them at all without going to the solutions or asking someone online, I sincerly hope the real exam is much more straight forward. I am also having problems with #12, I can calculate the change in enthalpy for the water and the mass flow of the dry gas and the change in enthalpy for the wet gas but im failing to see how the solutions make sense for calculating the wet gas volume and mass flow, the total Btu's transfered from the dry gas to the water should be equal so the mass between the dry gas and water is what has to be different, the dry gas mass can be calculated from teh ideal gas law but the gas enthalpys given are for the wet gas.

I was wondering if I could get your yahoo IM or email or something since I am going to try to power through the rest of the 6 min solution problems this weekend and it would be great to have some help since I dont know anyone else taking this exam.

 

[dagget]

Hello Dagget,
I have been working through and am noticing the 6 min solutions questions are not very easy and take me way longer than 6 min to solve if I can even solve them at all without going to the solutions or asking someone online, I sincerly hope the real exam is much more straight forward. I am also having problems with #12, I can calculate the change in enthalpy for the water and the mass flow of the dry gas and the change in enthalpy for the wet gas but im failing to see how the solutions make sense for calculating the wet gas volume and mass flow, the total Btu's transfered from the dry gas to the water should be equal so the mass between the dry gas and water is what has to be different, the dry gas mass can be calculated from teh ideal gas law but the gas enthalpys given are for the wet gas.

I was wondering if I could get your yahoo IM or email or something since I am going to try to power through the rest of the 6 min solution problems this weekend and it would be great to have some help since I dont know anyone else taking this exam.

My experience with the 6 min solutions is that they are not. Many of them take more than six minutes and one or two of the answers are just incorrect (looking through my notes from the review class, 12 is one of those). While the 6 min solutions are good for working different problems, etc. the actual test is almost exactly like the NCEES practice exams. They put that book out for a reason, and if you can work those problems comfortably you should be on track.

I will scan the solution from my review class and post it shortly (assuming that the upload widget doesn't get me). The previous responses I actually sat down and worked them out again, but I don't have time to do that today at work.

 

[dagget]

Here are what I have in my file for 12. The neat version is from the review course, the messy one is what I did myself during my practice. See the note on page 2 about the book solution being incorrect.

6ms_12.pdf

 

[rppearso]

Wow this is it, its go time in the morning, after 4 years its going down. 12 hrs left and 2 hrs left before bed time whew.