Mole Map Model

Description

The mass and volume of 144 uniform objects are determined. Based upon these measurements, the mass and volume of one object are determined, as are the mass and volume of a gross of objects. The analogy involves extending one gross to one mole, and changing the objects from visible, macroscopic particles to atoms.

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Set

Chemical calculations make use of many factors which often confuse beginning students. The "mole map" is a successful algorithm for many of these students. The mole map, in one of its most common variations, makes use of three kinds of factors:
1. molar mass
2. number of particles per mole
3. factors from formulas or balanced equations.
The graphical representation of the mole map algorithm is given below:
To use the algorithm, a problem is first interpreted in terms of a map route. For example, find the maximum mass of sodium chloride that can be produced from 3 x 10²³ atoms of chlorine. Chlorine atoms are assigned the subscript A, and sodium chloride units are assigned the subscript B. The first step involves converting from atoms to moles of atoms. The factor for this, N, is Avogadro's number. The next step involves going from a number of moles of chlorine atoms to a number of moles of sodium chloride. This comes from the formula of sodium chloride, NaCl. The final step comes from the molar mass of sodium chloride, 58.5 g NaCl/ mol NaCl. The steps along the path are shaded in the figure in the following diagram:
In the model for this algorithm, the gross, gross-mass, and gross-volume are determined. Students can practice with calculations that parallel those of the conventional mole map.

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Procedure

Count out 144 uniform objects such as beans or beads.
Place the objects in a 100-mL graduated cylinder. Estimate the volume.
Determine the mass of the objects.

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Handout

Name _____________________________ Class _______

Teacher______________________________

DoChem 023 Mole Map Model

Mass of container =
Mass of beads plus container =
Mass of beads =
Estimated volume of beads =
Mass per bead =
Volume per bead =

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Handout Makeup

Name _____________________________ Class _______

Teacher______________________________

DoChem 023 Mole Map Model

Watch the pictures. Use this sample data.
Mass of container = 10.56 g
Mass of beads plus container = 50.00 g
Mass of beads = ______________g
Estimated volume of beads = 84 mL
Mass per bead = ____________ g
Volume per bead =____________ mL

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Teachers Guide

Purpose

To study a model of a chemical calculations algorithm.

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Materials

(for 10 students working in pairs)

5 triple beam balance
5 weighing container
5 100-mL graduated cylinder
1000 uniform beads

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Lab Hints

This is a straightforward way to illustrate the mole concept. Some teachers believe that this concrete approach helps students who are nearly ready to grasp the mole concept.