Organic Chemistry Lab 315 Fall, 2014 For Tues., Sept. 16, we will meet in room 310 Planetary Hall at 1:00 p.m.

DUE DATES Today –No report due. –At end of lab -- copy of laboratory notebook pages for today's work – finish crystallization (details later). Next Week –At the beginning of class, “Crystallization Report” (Instructions posted separately) –Spectroscopy Problem Set problems Part I (found linked to experiment list page).

Graded Materials You can look at your Crystallization notebook copy, but you cannot keep it. Please return it to me today. –Most common errors were in “Purpose” – again merely copying the lab manual with no elaboration (“two unknowns/two solvents”). –Neglecting to weigh the storage container when the Manual explicitly said to. –Some of you need to record more carefully the procedure and observations – too sparse

Graded Materials Melting Pt. and Refractive Index Report –A common mistake was in citing physical properties of knowns and identified unknowns. –Citing physical properties was the reading assignment for the first week. The “Lab Reports” page made special mention of it and provided a link. –The Manual was very explicit about approved sources (CRC Handbook, Merck, and DOC). No others are allowed. –All compounds have unique identifying codes in the sources, and these must be given as part of the reference, as explained and illustrated in the Manual.

Graded Materials Melting Pt. and Refractive Index Report –Too many of you ignored the temperature when recording the refractive index. The temperature is important and must be recorded. n D 23.5 = –The temperature is recorded for the original measurement as well as for the temperature-corrected measurement that is compared to the literature value –The Report Form was explicit in telling you to perform your temperature correction on that page – how could that be ignored? –Fairly liberal in grading written report. Again, please read instructions!

In Lab Today Finish crystallization experiment (two) –Weigh container + product (and container if not done last week). –Put product in vial (see next slide). –Determine m.pt. –Affix label (see manual/Pavia for information to include on label). Store in class drawer. –Turn in product with Report next week. Get products ready TODAY – there will not be time next week for you to fix a label, etc.

Notes Transferring a solid to a vial If funnel bottom is not available, make a funnel from a small piece of paper.

Percent Recovery whole = all of that with which you began part = that which has been isolated Remember, you cannot achieve (nor expect to) 100% recovery. Some of the original substance was soluble in the solvent at 0 deg., and some of the original material in the vial was an impurity. Review significant figures for use in Recrystallization Report calculation.

Next Week Next week you will be given a liquid unknown to identify by: –Boiling point (new technique of distillation) –Refractive Index –IR spectrum