身近な素材を用いた結晶に関する教材の開発 : 凍結防止剤用塩化カルシウムを利用して

抄録

The purpose of this study is to develop a teaching material on crystallization and to examine the utilization of the crystal in order to arouse pupils' and students' interest in crystals and learn about it effectively. We made a highly-pure crystal from antifreezing agent, which is a familiar material. It consists of CaCl_2・6H_2O, the same ingredient as Antarcticite. Using the crystal, we examined ways of utilizing it for an experiment showing how the mineral crystal is formed. This teaching material has the following characteristics: a. A familiar material is used. b. A highly-pure and beautiful crystal can easily and cheaply be made. c. A crystal equal to a naturally occurring mineral can artificially be made. d. The melting point of CaCl_2・6H_2O is 29.6℃, making it possible to safely study the crystallization and melting of the crystal. e. By using CaCl_2・6H_2O, aspects of crystal growth and the experiment on the formation of the mineral crystal can be observed easily. In summary, we found that the experiment of crystallization treating the antifreezing agent can be utilized safely and effectively as a teaching material.