# Week 32 – The Return of the Mole

On the macro scale, if you have 10 small glass marbles and 10 large clay bricks, what is similar and what is different?  Well, clearly you have 10 of each (similar) but the materials have different masses (difference), with large clay bricks having more mass than small glass marbles.  Thinking about everyday items and quantities isn’t too bad.  However, in chemistry, we have to think about atoms and molecules (things that are incredibly small).  When we work with visible amounts of substances composed of atoms or molecules, we have to work with enormous numbers of those substances.  This brings us back to everyone’s favorite topic: The Mole.

In Unit 3, you learned that 1 mole is equal to 6.02 x 1023 “things” – such as atoms, molecules, or literally anything you want to count.  If you had one mole of glass marbles, you would have 6.02 x 1023 glass marbles.  If you had one mole of clay bricks, you would have 6.02 x 1023 clay bricks.

Let’s figure out the mass of one mole of marbles. One marble has a mass of 1.80 g.

• 1 marble x 1.80 g/marble = 1.80 g/marble
• 1.80 g/marble x 6.02 x 1023 marbles/mole = 10.8 x 1023 g/mole
• 10.8 x 1023 g/mole = 1.08 x 1024 g/mole

Your turn!  The Entry Task will guide you through another macroscale calculation (the mass of clay bricks) and then we will transition to the microscale (atoms and molecules).

Need a refresher on the Mole?  Watch the video below, then head back to the mole lesson in Unit 3 and review as needed.