Transcript Introduction to Unknowns.

Today’s Lab Lecture (10/14):
•Your questions…
• Introduction to Unknowns
Midterm 2:10 – 4pm in your lab
Rules:
Cell phones off and in your pack.
Do bring a calculator, but not a "computer". No sharing ...
Do not leave the room during the exam.
No extra note paper; use back of pages if necessary.
Please no questions during exam (unless you discover a serious
mistake). You can write: "if I understand the question this way ..."
No "late" exams... A midterm not taken earns the grade "F".
Introduction to Unknowns
For instructions and experimental details
see Chapter 10, pp.618 - …., in your Mayo text
For a list of Unknowns and their derivatives see our
ERES files
Sample “Unknown” problems are in our ERES Exam
Folder
Unknowns
Preliminary Tests pp.618 - 626
1. What is typical of the molecules of compounds that
have an odor?
2. Which organic compounds tend to have a
"pleasant" odor? And which tend to have a "bad"
odor"?
3. What characteristic features do you find in the
molecule structure of organic compounds that have
a color?
Unknowns
Preliminary Tests
1. What does the melting point tell you?
2. What does the boiling point tell you?
Preliminary Tests
(We do not perform tests on pp. 622 – 625)
•
What information do you obtain from the ignition
test? Compare with known compound!
•
How do you test for unsaturation? Compare with
known compound!
•
What information is obtained with the Beilstein
test (p.626)? Compare with known compound!
Solubility Tests
(pp. 626 – 627)
Do these carefully!
What type of information do you get if your unknown
1. is soluble in water?
2. is soluble in NaOH and in NaHCO3? (equation)
3. is soluble in NaOH only, not in NaHCO3? (equation)
4. is soluble in dilute HCl solution? (equation)
5. is soluble only in conc H2SO4?
6. is not soluble in any of the above solvents?
After the Solubility tests you will do
Classification tests
(specific for a certain functional group)
Once you have a reasonably good idea what your
unknown could be, you will prepare two
Derivatives
(related solid compounds with a defined, listed mp.)
Next time:
“Unknowns”:
- Aldehydes and Ketones
- Alcohols and Phenols