SEMIMICRO CHEMISTRY FOR THE BEGINNING STUDENT VERNON E. WOOD and H. RAWORTH WALKER, Jr. Mars Hill College, Mars Hill, North Carolina
IN THE spring of 1940 Mars Hill was building a new science hall. The entire fourth floor measuring 156 by 64 feet was allotted to chemistry and physics. The laboratory for beginning students in chemistry was a room 30 by 60 feet. It was necessary that this room provide individual lockers for 240 students. We had desks made to special specificationswith lockers one foot wide for each student's equipment. We allotted 10 square feet of working space for each student in a section. In order to take care of the equipment of each student in a cabinet one foot wide we decided to use semimicro methods wherever they were possible from the beginning of the first-year course. After correspondence with a dozen of the largest textbook publishers in America we found that there was no available laboratory manual providing for semimicro technics and equipment. The only thing left for us to do was to write such a manual for ourselves. The manual which we prepared covers work for general chemistry, a little simple organic, hundreds of spot-plate tests for ionic interactions, and systematic qualitative analysis. We have used this manual during the present school year in four laboratory sections with a total of 150 students in order to study the reaction to this type of work in comparison with that of student sections for the past two decades using macro methods. We have also used a very popular macro method manual in one of our sections this year. Our observation is that students enjoy the semimicro method. A beginning student is likely to be sloppy and careless in handling of equipment and chemicals. We have found that the introduction of semimicro technics a t the beginning of the course tends to make students much more careful in their procedures before they reach qualitative analysis. Another item of importance in our laboratory is the saving in cost of equipment and chemicals. We estimate that we have saved almost 75 per cent in the cost
of chemicals and 30 per cent in the cost of equipment without sacrificing any valuable student experience in beginning chemistry. Some new equipment was necessary but the extra cost of this was more than offset by savings in other items. For instance, enough was saved on filter paper alone to pay for six new Wilmar centrifuges. Materials such as test tubes, graduates, thistle tubes, and other equipment which must be replaced are so much less expensive in the sizes used in semimicro procedures that the lower cost of replacement gives the student a large annual saving. For shelf reagents, bottles equipped with medicine droppers and glass-stoppered indicator dropping bottles were used exclusively. Many of the tests are run on spot plates.
EL)UIPMENT I'OK
THE
BEGINNING COURSE
This work was not meant to be revolutionary in the type of experiments used. The regular classical experiments with some alterations and changes have been performed, with the small equipment of the semimicro technics rather than the larger equipment of the old macro methods. Those students repeating the course this year because of failures last year have all been enthusiastic about the change from macro to semimicro. They say that they can accomplish more in a shorter time.
