Saturday, November 20, 2010

LESSON 14: AVODAGRO'S NUMBER

Avogadro's number

·         Atoms and molecules are extremely small
·         Macroscopic objects contains too many to count or weigh individually
·         Amedeo Avogadro proposed that the number of atoms in 12.0g of Carbon be = to a constant (= to 1 mol of a Carbon)
·         This value is now called Avogadro's number and forms the basis of all quantitative chemistry
·         So what is Avogadro's number?
6.02 x 10^23
¤   1.0 mol = 6.02 x 10^23
·         One mole is simply a multiple of things
§  1 pair = 2
§  1 dozen =12
§  1 century = 100
§  1 mol = 6.02 x 10^23

HOW BIG IS A MOLE?
·         1 mole of meters would cross the entire galaxy over 3000 times
·         1 mole represents a huge number of particles
Example:
·         A sample of Nitrogen contains 1.56 x 10^23 atoms. How many mole of Nitrogen is this?


1.56 x 10^23 atoms      x      1 mol
                                      6.02 x 10^23 atoms   


  


  •      14.5 mole of I2 represents how many molecules?
14.5 mol        x        6.02x10^23 molecules
                                                1 mol






·         How many Formula Units are present in 0.34 mol of CaCl2?

0.34 mol      x      6.02 x 10^23 formula Units
                                               1 mol



- Kelly

posted by chemistry11 @ 3:25 PM

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