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Weighing Atoms

Weighing Atoms. Counting Atoms. Chemistry is a quantitative science - we need a "counting unit." The MOLE 1 mole is the amount of substance that contains as many particles (atoms or molecules) as there are in 12.0 g of C-12. mole = (mol) 602000000000000000000000. Mole.

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Weighing Atoms

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  1. Weighing Atoms

  2. Counting Atoms • Chemistry is a quantitative science - we need a "counting unit." • The MOLE • 1 mole is the amount of substance that contains as many particles (atoms or molecules) as there are in 12.0 g of C-12.

  3. mole = (mol) 602000000000000000000000 Mole • A mole is just a number pair = 2 trio = 3 quartet = 4 dozen = 12 baker’s dozen = 13 gross = 144

  4. Particles in a Mole Amadeo Avogadro(1776 – 1856) 1 mole = 602213673600000000000000 or 6.022 x 1023 Amedeo Avogadro(1766-1856) never knew his own number; it was named in his honor by a French scientist in 1909. its value was first estimated by Josef Loschmidt, an Austrian chemistry teacher, in 1895. ? quadrillions thousands trillions billions millions There is Avogadro's number of particles in a mole of any substance.

  5. Avogadro’s Number 6.02x1023

  6. How BIG is a mole? There are ~ 6.6 billion people on Earth How many Earths would it take to equal the population of 1 mole? 9.12 x 1013

  7. How Big is a Mole? One mole of marbles would cover the entire Earth (oceans included) for a depth of three miles. One mole of $100 bills stacked one on top of another would reach from the Sun to Pluto and back 7.5 million times. It would take light 9500 years to travel from the bottom to the top of a stack of 1 mole of $1 bills.

  8. If you had a mole of cats . . . They would create a sphere larger than Earth!

  9. If you had a mole of $$$$$ and you spent $800 billion dollars a day how many years would it take to spend a MOLEion dollars? 2.06 x 109 years

  10. In chemistry we don’t work with individual atoms or molecules because they are too small to be weighed or measured • We have to work with LOTS of atoms in order to measure them THAT’s WHERE THE MOLE COMES IN!

  11. of the in ATOMic Mass • This number on the periodic table tells us the mass in grams of 1 mole of atoms of an element • In other words…… 1 mol C atoms = 6.02 x 10 23 C atoms = 12g C

  12. of the in Molecular Mass Is the mass of a molecule = mass in grams of 1 mole of moleculesof So, 1 mole of NaCl atoms = 6.02 x 10 23 molecules which contains 6.02 x 10 23 atoms of Na (they weigh 23g) AND 6.02 x 10 23 molecules of Clthey weigh 35g) The weight of one mole of NaCl = 23+35 = 58g

  13. Mole - Calculation Practice

  14. Add up the atomic weights for each atom in the molecule: H2 hydrogen 2.02 g/mole He helium 4.0 g/mole N2 nitrogen 28.0 g/mole O2 oxygen 32.0 g/mole CO2 carbon dioxide 44.0 g/mole Examples of Calculating Molecular Mass of Compounds

  15. Stoichiometry of Chemical Formulas

  16. Using Moles in Chemical Equations • The coefficient in the balanced equation tells you how many moles react • Then you can calculate the weight in grams

  17. Weighing chemicals • 4Na + 1O22 Na2O • You need to weigh 4 moles of Na = 4 x23g = 92g of NaCl • It will react with 1mole of O2 = 32g • It will make 2 moles of Na2O = 62g

  18. The End

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