Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

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Sub Image2:Macro to Micro Structures
1) Atoms and Molecules2) Macro to Micro Structures 3) Energetics and Dynamics 4) Theory and Practice in Chemical Systems 5) Chemical Design 6) The Chemistry of Life 7) Chemistry and the Environment
8) Chemistry at the Interface

Unit 7.5 Water Purification
The need for pure drinking water on earth has caused mankind to develop methods for water purification, either by filtration or by using disinfectants, such as chlorine. Students are shown purifying water in a chemistry lab activity.
Video program cues: 31:45-40:05

Purifying water laboratory

Isoke Baptiste teaches the principles of filtration and phase separation in purifying water.



Oughton, J., Xu, S., Battino, R. (2001)' The Purification of Water by Freeze-Thaw or Zone Melting, 'Journal of Chemical Education, Vol. 78, No. 10, pp: 1373-1374.

Water disinfection

"What we’ve heard from the Indians of the continent, Latin America, and parts of Asia, is that the most important technology they need is safe drinking water. In Bangladesh, the monsoon rains came and stayed two months longer than usual, and literally flooded much of the country. The irony of this is that people can’t drink this water. They can’t drink it because of pathogens in the drinking water. We had the problem in the U.S., and we used a variety of technologies, the most significant being using chlorine. The chlorine kills the pathogens, and we can drink the water safely. But you can’t really take chlorine and the technology you need to work with it into a small village in Bangladesh, because of the reactive nature of the chemical. But you could take a bottle of hydrogen peroxide, and Calais pills, which would attach themselves to the pathogens. The hydrogen peroxide and the Calais would then kill the pathogens, and you could drink the water safely. It could be done very inexpensively. We haven’t solved this problem, but that’s our drinking problem. We started with water disinfection 20 years ago, and we still want to do it."

Dr. Terry Collins
Professor of Chemistry, Carnegie Mellon University


Hogue, C. (2001)' Chloroform and Cancer, 'Chemical and Engineering News, Vol. 79, No. 44, pp: 11.

Proceed to Unit 7.6 arrow

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