EVAPORATION OF METHYLATED SPIRIT AS AN ALTERNATIVE METHOD OF RADIOACTIVITY DEMONSTRATION IN PHYSICS AND CHEMISTRY AT SECONDARY SCHOOL LEVELS

Abstract

Practical demonstrations by teacher and learner, especially in Science Education, make teaching-learning process pragmatic, learner-centred, easier to understand, and more appreciated. Also, it has been observed that radioactivity is one of the important topics in Physics and Chemistry at Secondary School levels. Unfortunately, its concept appears abstract and illusion in the minds of the learners due to lack of practical demonstrations or experimentation of the theory. The reason for such deficiency may be attributed to hazardous nature of radioactive substances, strict legal regulations on their exposures (both at the international and domestic levels), associated risk during transportation and handling, etc. The essence of this research is to devise a way of practically demonstrating radioactivity by utilising a non-radioactive substance that is cheaply available with high level of sustainability and potential to exhibit decay. Specifically, methylated spirit was used as the non-radioactive substance in this study. It was put in a syringe clamped vertically with an open end facing up and timing of its evaporation was performed separately for intervals of 10 minutes and 15 minutes. In each case, the volume of the methylated spirit left was recorded and the data obtained were analysed It was observed that the volume – time relationships were of exponential decay characteristic supported by empirical formula governing radioactivity, notwithstanding the time intervals considered. For 10 minutes interval consideration, the results showed evaporation constant (which is analogous to decay constant), and half-life to be 8.14 x 10-4 min-1, and 851.4 minutes respectively whereas in the case of 15 minutes interval, they were found to be 8.40 x 10-4 min-1, and 825.0 minutes respectively. Hence, it could be adjudged that methylated spirit is a promising non-radioactive substance for practical experiment/demonstration to make teaching and learning of radioactivity learner-centred for a better understanding of the topic in Physics and Chemistry at Secondary School levels.