Final grades

Dear class,

We have finished grading the final and your course grades have been computed. I will endeavor to return these to you at the start of ChE110B. Alternatively, you may stop by my office if you do not get yours back in class next week.

The statistics for the final are:

• average - 61% (62% with bonus from problem session)
• standard deviation - 13% (13% with bonus)
• maximum score - 84% (87% with bonus)

The statistics for the course grade are (with bonus):

• average - 70%
• standard deviation - 10%
• maximum score - 90.7%

The letter grade distributions are as follows:

• A - 27%
• B - 37%
• C - 23%
• D - 8%
• F - 5%

A detailed plot of these distributions can be found on the course webpage.

I enjoyed teaching you all this quarter and wish you the best of success in your future endeavors!

Cheers,
MSS

Study break

Here's an interesting little mathematics / statistical analysis of the NCAA tournament that you may find to be a nice reprieve from your finals studying:

http://fivethirtyeight.blogs.nytimes.com/2011/03/15/when-15th-is-better-than-8th-the-math-shows-the-bracket-is-backward/?hp

These authors show that lower-ranked seeds actually have a higher probability of making it to the sweet sixteen, elite eight, and final four than mid-ranked teams. It's a problem ripe for population balances and rate equations, in truth not really all that different from mass balances and chemical kinetics.

Go Gauchos!

MSS

Office hours tomorrow

Hi class,

Just a small update to my office hours tomorrow. In the afternoon I will be available 4-5:30pm, not 3:30-5:30 as originally indicated.

Cheers,
MSS

Common mistakes on HW9

Dear class,

If you would like your HW9 back, you can retrieve it at the review session tonight or see me in my office tomorrow. Here are a few common mistakes we noticed in grading it:

Problem 49:

Some students did not realize that entropy increases for the nonideal compressor case. The corresponding curve in the Mollier diagram should start at the same place as the ideal case, but then move both up and over to the right, in the direction of increasing entropy. The endpoint will not be the same, although it will intersect the same isobar.

Problem 50:

Some students calculated for the turbine:

W_real = W_isentropic / efficiency
This is the right expression for a pump or compressor, but for a turbine it should instead be:
W_real = W_isentropic * efficiency

Cheers,
MSS

HW9

Hi class,

Please do attach the Mollier diagram that you work in problem 49 to your solutions. If you would like another copy, you can print one out from the online pdf of the homework assignment.

Cheers,
MSS

Final and review session

Dear class,

The final will be Wednesday, March 16, from 12-3pm. It will be open book and one page of notes, similar to the midterm. You should bring a calculator, your book, writing utensils, and your notes page. If you would like to use the first page of the fundamentals handout, and write your additional equations on the back, that would be fine as well -- but in total you should only have one page of notes to bring. The format of the final will be very similar to the midterm, but longer in proportion with the three hour time block.

I will hold an open question-and-answer review session on Monday, March 14 from 6-8pm in Engineering II 1519. Feel free to stop by whenever is convenient during that time to ask questions.

I will also be available to chat during office hours on Tuesday, March 15, from 10am-12pm and from 3:30-5:30pm. My office is Engineering II 3321.

In addition, I will be handing out grade statistics sheets for each student on Friday at the end of class so that you will be able to see how you are doing in the course going into the final.

Cheers,
MSS

Common mistakes on HW6 and HW8

Dear class,

We noticed that there were a number of mistakes on HW6 and 8 involving unit conversions. It is essential that you carry units throughout all of your calculations so that can keep tabs on conversion issues. To avoid a lot of writing, you can keep your equations in analytical form until the final step when you plug in actual values of variables.

Cheers,
MSS

Common mistakes on HW7

Hi class,

Here are some common mistakes that were made on HW7. Please check to see if you made these so as to avoid them in the future.

Problem 32: "well-insulated" implies "adiabatic" - which means Q = 0, not necessarily that delta(T) = 0 (although with an ideal gas in a process that also does no work, delta(T) will equal zero).

Problem 33: need to use absolute temperatures with the efficiency, Qc, and Qh equations.

Problem 34: need to use consistent units with the Q=n*cp*delta(T) equation

Problem 38: constants in table c.1 have units (e.g. B has units of 1/Kelvin and C has units of 1/Kelvin^2); basically another reminder to take care with units and make sure that they match up.

Cheers,
MSS