The Mole:  Counting by Weighing

A mole (not the animal) is a unit of measure in chemistry, defined as 6.02 x 10²³ units of any substance, a huge number.  One scientist made a back-of-the-envelope calculation of how heavy a mole of moles (the animal) must be. The answer: That many furry critters would be about as heavy as a planet.

The rationale for the mole:

• Atoms and molecules react on a “count” basis, that is, in simple whole number ratios.
• Atoms are too small to be able to count out the number and ratio of the atoms/molecules needed
• Weighing is a practical substitute for counting
• A “mole” is the name given to a number: 6.02 x 10²³
• This number equals the number of carbon atoms in 12 grams of carbon-12

For tutorials on balancing:

http://www.preparatorychemistry.com/Bishop_Balancing_Equations_frames.htm

http://www.preparatorychemistry.com/Bishop_bal_eq_Flash1.htm

For a tutorial on stoichiometry:

http://chemistry.alanearhart.org/Old/Tutorials/Stoichiometry/index.html  This link is out of date and needs to be updated.

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An animation of the process of dissolving NaCl in water is found at the following link:

http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/thermochem/solutionSalt.html

Science progress: New understanding of the 100 year old Haber Bosch reaction for synthesizing ammonia:

http://www.sciencedaily.com/releases/2011/11/111111152240.htm