The Properties of an Ionic Compound Time: Format: Cat. No.: Price: Supplier:
4 minutes Color, Super-8 Film Loop 580707 $22.
Encyclopedia Britannica Educational Corporation 425 N. Michigan Avenue Department 1OA Chicago, IL 6061 1
My accelerated tenth grade chemistry students are used to a wide variety of audio-visual aides, hut this loop has won our in-class "Academv Award." Even thouah I show parts of it several times during the course of the year, they seem to want to see it again and again. The students are excited by the animation of the ionic crystal as its vibration increases before it melts. and bv the livelv . way. it dissolves in polar solvents or "rejects"' the attempts of non-polar solvents. I have found this Super-8 film loop to be one of the few visuals that actively illustrates the attractive and dissociative forces involved in dissolving, as well as the chemical differences between dissolving and melting. The formation of free sodium and chlorine from the electroysis of molten sodium chloride is also shown. This loop quickly illustrates several rather abstract chemical principles and can be shown several times during the year. The students will not mind the re-runs. Cedar Ridge High School Old Bridge. N.J.
Free Film Loan Service Word comes to me that Association Films, Inc. offers 16 mm, sound and color, films for free loan to teachers across the country. They represent business organizations and government agencies who wish to distribute films free to schools, hut the borrower must pay the return postage which is nominal. I have not personally dealt with this firm so I would like to hear from you about this service. Write to the film center nearest your location for their brochure and more information. Association Films, Inc.: 410 Great Rd., Littleton, MA 01460 600 Grand Ave., Ridgefield,NJ 07657 324 Delaware Ave., Oakmont, PA 15139 5791 New Peachtree Rd., Atlanta, GA 30340 512 Burlington Ave., La Grange, IL 60525 6420 W. Lake St., Minneapolis, MN 55426 8615 Directors Row, Dallas, TX 75247 6644 Sierra Lane. Dublin. CA 94566
We thank Edna Hudson for her contributions to this column. We encourage all of you to send us your reviews so that we can truly be a clearinghouse for the most useful materials to the chemistry student. Ouestlon Department H. C. from Massachusetts asks if anyone knows where to get the filmstrip, "Safety in the Laboratory," a cartoon which is in color. 66 / Journal of Chemical Education
