A LAP on Moles: Teaching an Important Concept John lhde WBUSBUWest High School 1200 W. WauSau Avenue Wausau, W154401
LAP stands for Learnina Activitv Packet. The ohiectives of the LAP on moles includ;?understanding the basic concept of the mole as a chemical unit, knowing the relationships between the mole and the ittomic weights in the periodic tahlt, and b r i w able to solve hasic converiiion prohlems involving grams, moles, atoms, and molecules. The activity begins with a five-question pre-test designed to let the student determine for himself whether or not he needs to work through the LAP. Solutions to the questions are included at the back of the packet so that the student can determine whether or not he needs to complete the LAP. The main section of the LAP is essentially a programmed learning exercise in which the student is given information about the unit, the mole, its relationship to the atomic weights in the periodic table, and the relationship between atoms, molecules, moles, and grams. I t also includes information dealing with the usefulness of chemical formulas. The LAP tries to focus the student's attention on the power and farreaching significance of the mole concept. Each section of the LAP is followed by a short self-test to enable the student to determine whether~hehas mastered the ideas being taught in that section. Solutions to each problem are included in the hack of the LAP so that the student can determine whether he is ready for the next section. I have tried to include in-the information not just the mathematical relationships hut also a feeling for the power of the chemical formuln and all thv information thnl can he derived irom it. Examples of Imic conversluns are included
58
Journal of Chemical Education
to help the student see the logic behind the use of conversion factors. Althounh the maior thrust of this lesson is the basic understanding of the h o l e concept and its use in gram-mole conversions, I have included a diagram near the end of the exercise which attempts to draw thestudent's attention to the implications and interrelationships of the mole in chemistry. The diagram is shown below and proves useful during the introductory course whenever some new aspect of the mole relationship is introduced (e.g., stoichiometry, gas laws, molarity). Copies of the LAP on moles are available from the author on request. liters of A, (volume)
\
atoms or
4
molarity of A (molesfliter)
Jr
moles of A
grams of A
molecules of A (Using coefficients from balanced eauations)
II atoms q moles of B or molecules of B
rJ
liters of B
I
I
grams of B
\
molarity of B
This mu IMWe co m n wl I mntah rmrt,concise a m * ol ~pscltc methods teacnerr have found usell in leaching var 0"s o#niculIcan. cepts. Often readers will be able to obtain further details or materiais, such as class handouts, tram the author.
