Re: Chem 3610/3611/3620/3621

Moderator: Ron Robertson

Re: Chem 3610/3611/3620/3621

Postby Holly Jones » Fri Nov 04, 2016 3:44 pm

Hi Dr. Robertson, I'm looking over 28a and I think I'm confused on the wording of the question. What is meant by "at each stage"? And the line that in the derivation we called z sub a, is it supposed to be the same as y sub a or are we supposed to choose where z sub a goes? I hope my question makes some sense... Thanks!
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Fri Nov 04, 2016 4:46 pm

Oops! I meant to wait until Monday to assign 28a - I meant to assign 26a for Monday. Oh well, I will assign 26a on Monday as well as 28a.

Now to answer your question about 28a because we have covered enough material to answer it. "Heated" means we increase the temperature without changing the composition. This would be a verical line on the graph. "At each stage" means when we cross the line from 2 phase behavior to 1 phase behavior. Generally you find the compositions at the lowest temp on the graph (in the 2 phase region) and indicate what is happening to them (what are the trends in the compositions) until you cross into 1 phase. To your last question the overall solution composition is labeled in terms of B on this graph. The ZB would be 0.8 and your tie line would give you the MF composition of each phase in terms of B. Hope this helps!
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Wed Nov 09, 2016 7:39 am

Reminder: Quiz today at the beginning of the period. You may want to bring your own ruler. Be on time!
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Thu Nov 10, 2016 2:50 pm

I have the quiz graded and a key has been posted outside my office door. I will hand back the graded quizes during lab today. Other students can drop by the P Chem lab and pick yours up.

Also, please come by the office, look at the answer key, and get Exam #3. Feel free to take photo shots of the key. I went over the exam in the help session on Tuesday.
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Thu Nov 10, 2016 4:18 pm

Oops! The reading assignment is pp. 782 - 793 not 728-793 . . . Sorry about that
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Sat Nov 12, 2016 9:35 pm

No help session on Tuesday this week

I need to have some dental work done on Tuesday afternoon and so will be unable to run the Tuesday help session. If there is enough interest I might could do a Monday or Wednesday at 5 pm. Post here if you want to schedule.
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Re: Chem 3610/3611/3620/3621

Postby Holly Jones » Sun Nov 13, 2016 10:04 pm

Wednesday at 5 works for me.
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Mon Nov 14, 2016 3:22 pm

Help Session

11/16 (Wednesday) at 5 pm with location TBA (but probably E306)
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Re: Chem 3610/3611/3620/3621

Postby Holly Jones » Mon Nov 14, 2016 6:21 pm

I am stuck on this phase diagram. Mine looks nothing like the reference. Were we supposed to only have one single temperature for the lower melting limit? I am bringing it to your office hours tomorrow but I thought I would see if I could get help this way first.
Holly Jones
 
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Re: Chem 3610/3611/3620/3621

Postby Ron Robertson » Mon Nov 14, 2016 6:34 pm

Remember that you are freezing and not melting. The end of freezing should be around 30 C for all the runs, but it will not be exactly the same. The beginning of freezing will be much different. I will be glad to look at it in the morning.
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