Publication Date



Background: Problems that I have encountered in teaching a CHEM 101 course “How much arsenic do we eat?” A gen. ed. for non-science majors. 17 times online and 4 times F2F.


Concentration, Amount and Counting by Weighing

UMass Amherst STEM Ed Institute Saturday Workshop 2/3/2018

Julian Tyson, Professor Emeritus, Department of Chemistry.

Session 1. Introductions.

Ice-breaker: The elementarity contest.

Setting the scene: “How much arsenic do we eat?” Why do we want to know? The Consumer Reports articles (Nov 2012 and Nov 2014)

Dealing with really big and really small numbers.

Session 2. Amount, concentration

Solids, liquids and gases. The “parts per” concept.

Session 3. Counting by weighing

The count equation. Rice grains (the bottle content problem), atoms and molecules.. Chemical formulas and balanced chemical expressions. The numbers in the periodic table. Applications in chemical analysis

Session 4. Scaffolding students.

More on the arsenic-in-rice story

Wee Mac’s Sandwich Shop and the Wee Mac dozen, bread + cheese + turkey (BCT)

From everyday experiences to parts per billion. Amount vs concentration. Sample problems.