A Few Examples Illustrating the Molecular Weight Distribution of Polymers

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 12 Issue 4 (2007) pp 240-244

A Few Examples Illustrating the Molecular Weight Distribution of Polymers

M. Pilar Tarazona and Enrique Saiz

Departamento de Química Física, Universidad de Alcalá, 28871 Alcalá de Henares, Spain, enrique.saiz@uah.es
Received September 18. 2006. Accepted June 30, 2007.

Published online: 4 August 2007

Abstract. University students of introductory general chemistry can be perplexed when they are introduced to the dimensioned quantity, the Avogadro constant (N_A = N_A mol^–1). They may be awed by the enormity of its numerical part (Avogadro’s number) and confused by its numerator-less units (mol^–1). To ease students’ discomfort in dealing with this quantity, it is recommended that general chemistry lectures not stress the enormity of N_A and simplify the units by expressing a numerator (things/mol). It is further recommended that N_A be interpreted as unity. Lecture notes are presented that demonstrate the unity-factor interpretation, followed by questions designed to affirm students’ understanding of the mole concept.

Key Words: In the Classroom; general chemistry; Avogadro; units

(*) Corresponding author. (E-mail: enrique.saiz@uah.es)

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