A simple analogy to help students understand ionic concentration is presented. A common problem among beginning chemistry students is the failure to recognize that in a solution containing 0.1 mol L-1 sodium chloride, the concentration of chloride ion is 0.1 mol L-1, not 0.05 mol L-1. Similarly, many students do not understand that in a solution containing 0.1 mol L-1 magnesium chloride, the concentration of chloride ion is 0.2 mol L-1. To help students overcome such problems, an analogy has been developed in which a salt such as sodium chloride is compared to a unicycle, consisting of a frame and a wheel; magnesium chloride is compared to a bicycle, consisting of a frame and two wheels; and so on. Complete (i.e., 100%) dissociation is assumed throughout the discussion.
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Citation
Last, Arthur M. J. Chem. Educ.1998 75 1433.
Keywords
introductory, high school chem, teaching, learning aids
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