ed~tedby RON DELORENZO M~ddleGeorg~aCollege Cochran Georg~a31014
An Alternative Introduction to the Mole Fraction Alvan D. White Stockport College of Technology Stockport SKI 3UQ, UK
In a note in this Journal,' DeLorenzo described his method of introducing the concept of the mole fraction. In it he uses the analogy of the female fraction of a class of students. This type of introduction is very similar to the one I have used for a number of years. In this case, I make only the minimal change of a single letter by starting with the MALE fraction (as opposed to the MOLE fraction). This is then defined in terms of my current class in the following way male fraction = number of male students
number of males
+ number o f females + number who aren't sure
With this somewhat unexpected twist at the end, one can usually he sure of raising a laugh from the class. This "humor" helps the students to grasp the concept, and it then can he placed in its chemical context via the following intermediate fraction: male fraction =
number of males total number of people
' DeLorenzo, R., J. CHEM.Eouc., 57,733
Editor's Note: Commercial producls are of interest lo most of us Occilsmnally commercm producls are aduen sea 'n r a y s lnal scent srs w e r l on Far example. there are several commercial thirst quenchers on the market (such as Gatoradem.Energade? and Quickicke) that are used by professional s p players ~ who believe that these drinks we the best way to replace fluids and eletrolytes (potassium, sodium). Yet, most of these drinks are hypertonic (have an electrolyte concentration greater than normal bodv fluidsland actuallv cause dehvdration in muchthe same wa, tnat armmg ocean Haler doer i e . DI araw,ng om, f ".as ,no lrlc SIO~JC~ 10~mosi5Water is normal, lne oesl ~ t to dar nn lo replace IOS! fl.im W in a proper aiel clec1ro)le replacement or us.a.1) no1 necessary.' This bit of informationcould be kasiiy worked into example problems or mentioned in brief to a chemistry class while studying osmosis and osmotic pressure. Reader contributions that will produce insight concerning commercial products are strongly encouraged.
'
Sportsmedicine Digest, 3, No. 5: Science News, 104.
8/15181, p.
(1980).
Volume
59
Number 2
February 1982
153
