High School Biology-Chemistry SMILE Meeting
23 November 2004
Notes Prepared by
Carol Giles [Collins
HS] Bread Mold, Continued
We examined the (hoped for) moldy bread from Carol Giles' presentation two weeks
ago. They had been sitting in Ben's office for the last two weeks. All of the
"experimental" slices did in fact grow mold, and every single control slice was without
mold—a spectacular result!. As a class we found about a dozen different species of mold
that we had picked up swabbing various areas in the classroom.
It was a beautiful phenomenological lesson, Carol!
Walter Kondratko [Steinmetz HS]
A handout contained the following information:
MELTING POINT DETERMINATION
Walter brought 6-8 sets of apparatus that let us measure the melting points of chemicals
accurately and easily. The instruments have a port into which a thin capillary tube containing an
unknown (solid) chemical is placed, and a microscope which looks in on a hole in the
port so that we can see whether the material in the tube is solid or liquid. A thermometer
simultaneously records the temperature in the port, so that the melting temperature can be
determined. The experiment was a great success with measured melting points generally within about
± 4 °C of the accepted/standard values.
In chemistry the two major ways of determining a compound's identity are through
chemical and physical properties. In this lab, the student will investigate the
method of using a physical property (melting point) to determine the identity of
goggles and aprons.
Compounds of various melting points, capillary tubes, MEL/TEMP
apparatus for measuring temperatures, and
Name two methods for determining a compound's identity.
Can a melting point analysis be used on a liquid compound? Explain.
Obtain a known sample of Vanillin and 2 unknown samples from your instructor (be
sure to record the letter of the unknowns).
Obtain three capillary tubes and fill them to a height of 2 mm with the
Place the tubes into the MEL/TEMP apparatus. Start with a relatively low
temperature setting (2 or 3) and slowly increase the temperature. Record
the temperature at which each melts.
When all compounds have melted, turn off the MEL/TEMP.
Look at the master melting point list and decide which of the compounds on the
data sheet has a melting point that matches your unknown compounds.
- MASTER LIST OF POSSIBLE COMPOUNDS USED FOR MELTING POINTS
|Lauric Acid||44 °C|
|Benzophenone ||48 ° C|
|Urethane||50 ° C|
|Diphenylamine||53 ° C|
|4-Methyl benzophenone ||56.5-56.7 °C|
|Stearic Acid||71 °C|
|Ethyl-4 aminobenzoate||89 °C|
|O-anisic acid|| 99 ° C|
This was an excellent hands-on lesson! Thanks,
Brenda Daniel [Fuller Elementary School] The Human Body,
Particularly the Skeleton (Handout)
Brenda passed around a handout describing the Foss Human
Body Module, which was developed at the University of California, Berkeley and published by Delta Education.
This handout contained sketches of the human skeleton entitled COUNTING
BONES, BONE NAMES, MUSCLE NAMES, and MR. BONES A-C.
Brenda discussed the human skeleton, using X-
rays as an example of how to view the skeleton. As an exercise we then taped our
fingers together, and then attempted to do normal activities
that require the use of our hands. We learned -- firsthand -- of
the importance of independent use of all
the digits in our fingers. Amazing and informative! Thanks, Brenda!
Notes taken by Benjamin Stark.