Concentration, Amount and Counting by Weighing UMass Amherst STEM Ed Institute Saturday Workshop 2/3/2018 Julian Tyson, Professor Emeritus, Department of Chemistry. Tyson@chem.umass.edu 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.