Challenging misconceptions about osmosis

 

Robert J. Kosinski & C. Kaighn Morlok

Tested Studies in Laboratory Teaching, 2009, Volume 30

Abstract

Osmosis is a traditional topic in introductory biology courses, but incorrect explanations of it are common. This laboratory allows students to estimate the water potential of potato cores using the weight change method and three different solutes: sucrose, glucose, and NaCl. The use of the three solutes does not interfere with the water potential determination, but does allow the students to assess three theories of the cause of osmosis—that it is caused by water concentration differences, by the binding of water to hydrophilic solutes, and by the simple number of solute particles (van’t Hoff’s Law).

Keywords:  osmosis, water potential, potato, van’t Hoff’s Law

University of Toronto, Mississauga (2008)