final exams and final grades

Dear ChE170,

Your final exams have been graded and course grades have been assigned. You can find information on grade distributions here. If you would like to pick up your exam, please stop by my office any time this quarter or at the start of the next.

I enjoyed the class this quarter, and we'll leave up the gallery for a while for all to admire your work. Good luck in your future courses and endeavors!

Cheers,
MSS

HW 5 pickup

Hi all,

If you would like to pick up graded HW5, I will be available in my office (or the lab next door) from 2-4 PM. (Chemistry 3219)

Sunyia

Review session for final

Hi class,

I will hold a question-and-answer review session for the final exam on Monday from 2-3pm in 1519.

Cheers,
MSS

Movies

Class-

If you're interested, here is a link to the website with the movies that I showed today in class:

http://multimedia.mcb.harvard.edu/

Also, I was able to find the NY Times article that Sam mentioned that describes the efforts to produce these movies (Thanks, Sam):

http://www.nytimes.com/2010/11/16/science/16animate.html

Cheers,
MSS

Cancer rates

In class today someone asked about cancer incidents and deaths over time. Here are several telling charts from the NIH:

http://www.ncbi.nlm.nih.gov/books/NBK20811/figure/A5099/?report=objectonly

http://www.ncbi.nlm.nih.gov/books/NBK20811/figure/A5100/?report=objectonly

http://www.ncbi.nlm.nih.gov/books/NBK20811/figure/A5101/?report=objectonly

As you can see from this data, death rates from stomach cancer have decreased over time, likely due to improved food practices (refrigeration, food storage and handling). On the other hand, lung cancer deaths increased dramatically in the 20th century, peaking around 1990. Other cancer rates have fluctuated somewhat.

Cheers,
MSS

Protein gallery

Dear class,

Your bonus projects have been posted in the hallway outside of 3301. They turned out quite nice! I encourage you to take a look at the gallery.

Cheers,
MSS

Guest lecture

Class,

I posted Prof. Doyle's slides from last Tuesday online at the course website.

Cheers,
MSS

Final reading assignment

Dear class,

I was just alerted of a typo in the course syllabus. The final reading assignment should be Chapters 17 and 20, not Chapters 7 and 20.

Cheers,
MSS

HW5 clarifications

Dear class,

A few clarifications about HW5:

Problem 2c - In the second part, it should ask you to find the time dependence of [U], not [U]SS.

Problem 3d - It is asking for the total concentration of the site, [S]0. You should express your concentration in molarity (or millimolar or micromolar units as appropriate).

Problem 4 - Insulin is NOT taken up by the cells; only glucose is. Also, when applying your pssa approximation, you should use it for insulin, not glucose.

Hope that helps,
Cheers,
MSS

Problem 3

Class,

I just found another small typo in problem 3. It should ask you to look for a maximum, not a minimum, in drug concentration, which will be higher than the buffer concentration. Chances are that this did not affect your solutions, however.

Cheers,
MSS

HW4, Problem 3

Dear class,

There is a typo in the problem set for problem 3. The typical surface tension of a bilayer should be 70 mJ/m^2 (milliJoules per meter squared). In the original problem set, it appears as microNewtons instead, which is an incorrect set of units for surface tensions.

Cheers,
MSS

Office hours

Dear class,

Due to my presence at the AIChE meeting this week, I will not be holding office hours. However, Sunyia will still be having hers. She also has an additional time this afternoon (see previous post).

Cheers,
MSS

Friday Office Hours moved to Monday

Hello class,

I will not be having my regular office hour this Friday, and will move it to Monday afternoon at 4 PM.

Sunyia

HW3 and HW4

Dear class,

Per the vote today, the due dates for HW3 and HW4 have changed:

HW3 due Tuesday 11/9 (formerly Thursday 11/4)
HW4 due Thursday 11/18 (formerly Tuesday 11/16)

I will distribute HW4 this coming Thursday so that it is given with two weeks advance of the due date.

Keep in mind your final two quizzes have not changed from their dates indicated in the syllabus, and will be on Tuesdays:

Quiz 4 on Tuesday 11/9 (covering Chapters 11-12)
Quiz 5 on Tuesday 11/23 (covering Chapters 15, 8, &16)

Cheers,
MSS

Drug discovery seminar

Dear class,

The Technology Management Program has a seminar next week from Roger Perlmutter, the Executive Vice President of Research and Development at Amgen. The title of the talk is "Building Better Medicines: Drug Discovery in the 21st Century" and it may be of interest to many of you who are thinking about careers in biotechnology and medicine. I imagine that you will be well-equipped to understand the content of the talk with what we've discussed in class so far.

http://www.tmp.ucsb.edu/outreach/pdf/LSPoster_Perlmutter_HR.pdf

Cheers,
MSS

HW1 solutions

Dear class-

The solutions to HW1 are now posted on the course website.

Cheers,
MSS

HW 1 pickup

Hi everyone,

If you would like to pick up your graded first homework before Thursday class, I will be available in my office (Chemistry 3219) from 3-5 PM tomorrow (Wednesday).

Sunyia

Problem 5 on HW2

Dear class,

At some point in this problem it asks you to prove that DeltaS(Ts) = 0. One approach would be to go back to the derivation for the free energy of folding with temperature that you did in HW1, where you had explicit expressions for DeltaS and DeltaH. Another approach might be to use a thermodynamic identity that you learned in your ChE110 classes. Hint: if you know G(T,P) then what is (dG/dT)_P, by definition?

Cheers,
MSS

Question

I was reading my Biochem book and it states that a closed system exchanges energy, but not matter. I though you said the opposite in class. Also, for today's lecture, I was confused on where the lecture is taking us. Are we studying the probability of empty sites that will later translate to sites on enzymes or some other typing of bonding in the cell?

Closed systems are those that can exchange energy, but not mass. Isolated systems are those that exchange neither.

The example worked in class was just a simple case to illustrate the properties of Boltzmann probabilities. We will not connect this specific example to any biomolecular process; however, the final, general equations that we arrived at, namely the connection between state probabilities and free energies, will be used quite extensively.

HW1, question 4b

Dear class,

There is a typo in part b of question 4 on the homework. It should say that the transfer free energy is N * (0.2 kcal/mol) and not N * (0.1 kcal/mol). An updated HW is posted online. Sorry for the confusion.

Cheers,
MSS

ChE170 logistics

Dear class,

Just a reminder from the syllabus: your current reading assignment is Chapters 1-2 in ECB3. Our first quiz will be next Thursday, 9/30, at the start of class, and it will cover this material.

Below I am also posting the complete office hours schedule for this quarter:

Mondays 11am-12pm, MSS - Eng. II 3321
Tuesdays 3-4pm, Sunyia - Eng. II 3201
Wednesdays 10-11am, MSS - Eng. II 3321
Fridays 12-1pm, Sunyia - Eng. II 3201

Cheers,
MSS

TA Office Hours this Quarter

My ChE 170 office hours this quarter will be in EngII, Room 3201, Tuesdays 3-4 PM, and Friday 12-1 PM, starting next week (9/28)! This room is the ChemE TA room, and it's on the third floor outside by one of the the stairs.

Sunyia

Final grades

Dear class,

We have finished grading the final and your course grades have been computed.

The statistics for the final are:

• average - 59% (63% with bonus)
• standard deviation - 16% (17% with bonus)
• maximum score - 92% (98% with bonus)

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

• average - 68%
• standard deviation - 13%
• maximum score - 92%

The letter grade distributions are as follows:

• A - 23.6%
• B - 29.1%
• C - 27.3%
• D - 9.1%
• F - 10.9%

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

Final review problem solutions

Dear class,

The numerical answers to the review problems suggested for the final are posted online.

MSS

Problem #48

On problem #48, since we are given that the gas is ideal (not steam, or methane, etc.) with a constant heat capacity and that the expansion is adiabatic, can we use deltaH = Cp*delta T to find the shaft work? But since this is also the expression to find the isentropic work, would the efficiency be 1.00?

The efficiency measures the work relative to the isentropic work. In the isentropic case, the exit temperature will be different from the actual temperature given. So, to compute the efficiency you will need to compute the new output temperature.

MSS

Review session

Class,

I will hold a question-and-answer review session for the final on Monday from 5:30-6:30pm in our usual classroom.

Cheers,
MSS

Problem #47

When solving for V in terms of V-vap and V-liq, is it ok to assume that V-liq will be negligible?

This is probably a pretty good assumption that will simplify your calculations, provided the temperature is sufficiently sub-critical and V-vap and V-liq differ quite a bit in magnitude (e.g., V-vap is ~1000 times as large).

MSS

HW9 question

For problem number 47 once 25% of the steam has condensed do we use the evap. column in the steam table to find the volume and pressure of the new state?

Think about what kind of process this is. It states that the condensation takes place in a rigid vessel. That means that the *overall* molar volume of the system must remain constant. That places a constraint on the overall molar volume of the final state, which is a combination of liquid and vapor molar volumes (via the quality). The other constraint is that the system is on the saturation curve. Those two constraints should help you find the final state, using the steam tables.

You will also need to apply the first law to figure out how the heat removed relates the properties of the system. Note that Delta H = Q / n does not apply here because it is not a constant pressure process.

-MSS

HW 8 Problem 40

Dear Class,

You should assume that the device in problem 40 operates adiabatically.

-Nathan

HW8

For number 40 on the homework, can we assume that the system is isochoric because in the book it says that for a steady state process, the mass and entropy of the fluid in the control volume is constant. Are we allowed to use isochoric equations to solve for q of the process?

You could use the equations for an isochoric process only if the volume per mole of the fluid stays the same throughout the process, not the control volume. Thus, if the conditions indicated suggest a constant volume per mol of the flowing streams, you can use isochoric expressions. If not, you will need to use more general expressions.

MSS

Problem 43

Dear Class,

There is a typo in Problem 43.
Problem 43 should read:
"Superheated steam at 500 kPa and 300 deg. C ..."
The online version has been corrected.

-Nathan

AIChE membeship

Dear Class,

Several student had problems with AIChE's membership website when attempting to join AIChE for assignment 6. As a result you may attach proof of membership to Problem Set 8 or 9 to receive bonus points for the final if you have not done so already.

-Nathan

HW8, problem 39

I am doing problem 39 on the homework and I am not sure how to calculate T2.

Remember that you now have multiple thermodynamic laws that you can apply to any process. Think about solving problems systematically by applying all of these laws. If you are still confused, go back to HW6 where you have solved problems for T2 exactly like this before.

-MSS

Problem 33 on Problem Set 7

Dear Class,

There is a typo in the problem set. For Problem 33 parts (c) and (d) the efficiency (eta) is 70% of the Carnot efficiency as it was in parts (a) and (b).

-Nathan

Hints for Problem Set 6

Dear Class,

Here are some hints for Problem Set 6.

Problem 29
You should assume that air is at 1 atm. You should be able to model air as an ideal gas to acceptable accuracy.

Problem 30
Propane is usually stored as a saturated liquid.

The equations used in this assignment generally offer good agreement with tabulated data for the conditions of interest. If you find that your |%error| is large (ie more than 10%) you have probably made an error.

-Nathan

Extension for HW6

Dear class,

I received a request to extend the HW6 deadline. I am willing to do this, but mainly because I believe it is very important after the midterm for you catch up to material that you did not understand. As such, you may turn in HW6 this Friday at the beginning of class.

However, HW7 will still be given out tomorrow (Wed) and it will still be due a week later (the next Wed). There will be no other extensions for homework given, except of course in extenuating circumstances on an individual basis. I expect that you should be starting on your homework sets well-before the Monday or Tuesday before they are due, in order to time-manage this course's workload with your other courses.

Cheers,
MSS

Antoine’s Equation and the Clausius-Clapeyron Equation

Dear Class,

When Antoine’s equation is combined with the Clausius-Clapeyron Equation DeltaH becomes:

DeltaH=BRT²/(C’+T) ²

There may have been a missing exponent when this equation was presented in class. Note that B, C’, and T have units of Kelvin. The US edition of SVA gives C in Celsius in Table B.2, therefore C’=C-273.15. International editions of SVA may already give C in Kelvin.

-Nathan

Questions regarding HW6

Some questions and answers-

The table C.1 has values of B divided by 10^3, but the examples in the book have 10^-3. Could that be a typo?

What the book is reporting is the value of B times 10^3, so that the actual value of B is a factor of 10^3 smaller. Think of the number listed in the table as a value x. Then, we have B*10^3 = x so that B = x * 10^-3. Similar for C and D.

I am trying to work on problem 4.2 part a, using the example 4.3 as a guide. So for the iteration of the mean heat capacity over R, how can I compute it without having a value for tau? Should I assume first it equals to 1, starting with T = Tzero, then getting a value for heat capacity, plug it into T = deltaH/Cp + Tzero. Then using the new T, with new tau , get another value for Cp, then another value for T and so on?

Yes, exactly. Remember, the mean heat capacity depends on both the initial and final temperatures. Consider constant pressure heating where the heat duty is specified. In this case, the first law is:

Delta H = Q/n

We can rewrite Delta H using the mean heat capacity and the temperature change:

(Tf - T0) Cpavg = Q/n

We can solve this for Tf, but it is highly nonlinear in Tf. Why? This is because Tf not only appears in the temperature difference, but it is part of the expression for (by way of tau). Setting up an iteration helps us solve this nonlinear equation:

Tf = (Q/n) /Cpavg + T0

You start with a guess for Tf and plug it in. The easiest guess is just to use T0. Then, you use this equation to continue to get new guesses for Tf until you converge on one value. At that point, you have found the value of Tf that solves the original equation.

Cheers,
MSS

Office hours on Monday 2/15/10

Dear Class,
I will have regular office hours on Monday (2/15/10) from 10-11am in Engr. II 3301.
-Nathan

Problem Set 5

Dear Class,

If you turned in Problem Set 5 on Monday and would like to work on it during your extension, you can pick up your Problem Set from me in my office (Engr. 3218) until 5:00 pm today or during office hours from 5-6 pm in Engr. II 3301.

Cheers,
Nathan

Classroom change reminder

Dear class,

This is a reminder that today's class will be our first in the new classroom, EII 1519. It is located in the new construction of the EII quad, on ground level immediately to the right of the large stairway as you walk up to Chemical Engineering.

MSS

Extension on HW5

Dear class,

Since there are a number of midterms this week and last, I will extend the deadline for turning in HW5 until Wednesday at the beginning of class. However, I will still hand out HW6 today.

Cheers,
MSS

Questions and answers

Here are a few questions that I received through email and responses that may be useful to you.

I was just wondering how much of the virial expansion we will need to know. I am assuming everything we learned, to be safe. But I was wondering if there was a certain emphasis you wanted us to have, such as where the equation comes from or solving a problem like the example we had in class.

What we covered in lecture should be sufficient for understanding the virial equation. Generally, anything presented in lecture is what you should know very well, especially since we are covering a lot of material in just 10 weeks.

When do you know where to use the virial expansion? In the book example and the one in lecture the values for B and C were given, indicating that the virial equation would be used. Is there a table in the book for the values?I couldn't find one. Or would we be given the values if they were needed?

Second (and sometimes third) virial coefficients are tabulated for a wide range of systems because they are often easy to measure experimentally, but I don't think the book has a table. Generally if we work a problem these values will be given. In your later courses, you may see a lot more of the virial equation because it is frequently used to model dilute suspensions and colloidal solutions. But for the purposes of modeling fluids, the cubic equations of state and, even more so, the generalized correlations are usually more accurate.

Are the isothermal compressibility and the thermal volume expansivity generally constant for a specific material, or do they vary with temperature and pressure? For an ideal gas can we assume they are constant?

In general, these parameters are state-dependent, and thus depend on the specific pressure and temperature of the system. They do depend on state for an ideal gas. I believed we derived the ideal gas expressions for these parameters in lecture, but it should also be in the book if you want a second perspective.

MSS

Review session for midterm

Dear class-

We will have a question and answer review session on Wednesday 7-8pm in room 3301, Engineering II.

Cheers,
MSS

Midterm Exam

Per our discussion in class, we will aim to have the midterm on Friday, Feb. 5 in class. If you have problems with this date, please email me before class on Wednesday. Otherwise, there will be no make-up midterms except for exceptional circumstances.

Cheers,
MSS

Correction to HW3, problem 10

Dear class,

There is a typo in problem 10 on HW3. The heat capacity for the vessel should be expressed in terms of pound-mass, not pound-mole.

Cheers,
MSS

Office hours on Monday (1/18/10) are canceled

Dear Class,

Office hours on Monday (1/18/10) are canceled since the power will be out in Engr. II and it is also a holiday. I will have extended office hours on Tuesday from 5:00-6:50 PM.

-Nathan

Office hours on 1/11/10 are canceled

Dear Class,

Office hours for Monday 1/11/10 are canceled. I will still have regular office hours on Tuesday in Engr. II 3301. You are also welcome to stop by my office, Engr. II 3218 on Tuesday. I should be available all day (9:00 AM - 5:00 PM).

Sorry for the inconvenience,
Nathan

Ch E 110A Office Hours

Dear class,

Office hours for Ch E 110A are as follows:

Prof. Shell (3321 Engr II)
Thursday 11:00 AM-12:00 PM
Friday 2:00-3:00 PM

Nathan (3301 Engr II)
Monday 10:00-10:50 AM
Tuesday 5:00-6:00 PM

-Nathan