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C. Rius-Alonso, D. Contrera-Lopez

Facultad de QuĂ­mica, UNAM (MEXICO)
At the Faculty of Chemistry, Universidad Nacional Autonoma de Mexico, the Organic Chemistry curricula has a laboratory for each of the courses, 10-12 different practical experiences are done. The students has several tools to do the experiments: A detailed manual for the experiment, with a list of reactants and equipment, the detailed procedure to do the experiment and a list of questions to check if the concepts were learned.

The groups have around 12 students per instructor, even that there is a very personal supervision of the instructor, the students has difficulties to understand each of the manipulation of the experiment.

In order to help the understanding of each step in the practical experiment a video of each of the experiments was done. A simple video would not be very useful for the reinforcement of learning, thus we decided to do an extensive editing of each experiment. The initial length of each video was from 45min to 1:30 hrs, this is very long to have the patients and concentration to watch it. It was decided to extract just the most important aspects to help the students learn the different concepts while watching the video.

After extensive editing the video we finished with a length of 8-12 minutes with the most important parts of the experiment highlighted in detail, with the help of slow motion, zoom, and overlapping text and graphics the video is very useful and illustrative for the experiment, and effort has been made to reinforce the most confusing part of the experiment.

For the Organic Chemistry I the following videos were prepared.

The video for melting point has a zoom of the crystals and the exact time of melting is observed, in order to reinforce the concept of melting a graphics of the crystal structure was done with the molecular modelling program Hyperchem, and submitted to a molecular dynamics experiment in order to start heating the crystal and show from the molecular scale the melting of the crystal. The graphics were overlapped as a transparent video within the video of the crystals melting. Two devices were used in the experiment the Fisher melting point apparatus and the Thiele tube. One of the advantages of using video is the possibility of getting very close and with magnification to the crystals and determines the exact moment of the melting.

Other videos were: Simple distillation, Fractional distillation Vacuum distillation, Elemental Analysis, simple crystallization, two solvent crystallization and extraction

All the videos were prepared in 3 different formats, from small size to a DVD quality. This allows us to deliver the videos either by web or by DVD to the students.

The student can watch the video before the experiment or after it in order to reinforce details of the experiment. Since the introduction of this tool and improvement of the student who use these has been observed.