Practicum
Tuesday, November 27th 2007 and Wednesday, November 28th, 2007, 1:00-3:50PM
The Practicum is a REAL TEST of your laboratory technique. You may use your books, notes etc. You mayNOTtalk to fellow students or ask questions of Gary or me.
Suggested Strategy:
1.For liquids: do a carefulsimple distillationat beginning of lab to get a boiling range. Remember things like flask (still pot) size, thermometer placement, drip rates - See Pavia!
2. For solids, take a MP range at beginning of lab.
3.Use the list of possible unknowns provided by Gary or in the back of the Pavia text to narrow the search to no more than four compounds based on BP/MP range.
4. Now do the alkene, alkyl halide and alcohol classification tests as needed. Four example, if you narrow down your unknown to only alcohols or alkenes, then just do the alcohol and alkene tests. Only consider doing all three types of classification tests if there is some discrepancy in your MP or BP ranges. If you do these tests do them one time – no repeats - and record your observations. Known compounds will not be provided (except for alcohols).
5.Using your boiling range and MP ranges and comparing any observations for the classification tests to your notes from the Alkyl Halide and Alkene tests done during the semester, determine the identity of your Unknown liquid.
6.CLEARLY identify your Unknown number and it’s name on the lab report sheets.
Clearly record the observed data (BP/MP ranges, results of classification tests, etc.) in
your lab report sheets.
7. In 2-3 sentences, give a reasoning for the identification of you unknown under the
“Based upon the following” section.
7. You will not submit a formal, typed lab report. You will turn in the report sheets
and attach your carbons to the end of your report.
The Lab Report Sheet and attached carbons with your unknown CLEARLY identified is due at 1:00PM on Tuesday, December 4th, 2007 for CHE 311-01 and on Wednesday, December 5th, 2007 for CHE 311-02. Gary will collect all practicum reports at 1:15pm sharp on each respective day. Practicum reports turned in after 1:15pm on either day will be considered late and subject to a penalty deduction.
Written Quiz
Friday, December 7th, 2007, 1:00-3:30PM, NSM C-213
Bring a pencil/pen, ruler and calculator
NOTE: only use of scientific, non-programmable calculators will be permitted. That’s right, you don’t need the fancy graphing HP/TI-80 something series/Casio or other similar calculators. No cell phones – turn them off or place on silent. No iPODs either – just listen to the music in your head!
Examples of things you should know:
- Theory, proper application and execution of all techniques:
- Why and when are simple, fractional, and steam distillation used?? Under what situations would you choose one over the other? Know proper placement of the thermometer bulb.
- How and why do you do a recrystallization?
- Extraction: how, when, and why?
- TLC: calculation of Rf values, why and when is it used.
- GLC: calculations of percentages of chemicals in a mixture; what is it?
- MP and mixed MPs – why do we take them? How does it help with identifying an unknown?
- Know any balanced chemical equations we have gone over except nitration. Know mechanisms, such as SN1 and SN2. You do not need to know EAS mechanism.
- How do you determine limiting reagents and calculate a percent yield??
- Classification tests, such as alkyl halide, alcohol, and alkene tests that were used this semester. I will not require you to know the chemical reactions (next semester you will have too), but you should know what to expect for positive and negative tests.
- You do not need to know details such as, how much of a certain reagent was used, etc. but you should have an inkling as to why we used certain reagents in ANY of the syntheses, reactions, and extractions.
- Go over your pre-lab notes, answers to exercises and lab reports, especially the sections where there are explanations given for the steps of a particular experiment. And most importantly, read Pavia as it extremely helpful!