1 pair of kicks (shoes) 1 dozen of eggs One 2L of cola reams of paper

So what unit do chemists use to count particles? Particles are so tiny, chemists use the unit of moles. A mole contains 6.02 x 1023 atoms. 602, 000, 000, 000, 000, 000, 000, 000

602,000,000,000,000,000,000,000 One mole of popcorn would cover every dry surface of the Earth to a depth of six miles One mole of stacked pennies would reach to the moon and back 16 times One mole of marshmellows would cover the US to a depth of 650 miles

1811- Avogadro- equal volumes of gases at the same temperature and pressure contained equal number of molecules 1861- Cannizzaro- developed atomic weights for known elements 1865- Loschmidt- determined the number of atoms present in given volume of air 1971- true value 6.02 x 1023 found

Recall the Law of Conservation of Mass Mass of reactants = mass of products Mass of starting substances = mass of ending substances 2 hydrogen atoms + 1 oxygen atom  1 water molecule

Law of Definite Proportions Regardless of amount, a compound will always be composed of the same elements in the same proportions by mass For example, two hydrogen atoms will always combine with one oxygen atom to produce one molecule of water

Moles  Particles Conversion (particles could be atoms or molecules) If you have three and a half dozen roses, how many roses do you have? What is the conversion factor?

Moles  Particles Conversion Particles  Moles Conversion

Convert 3.5 moles to atoms Moles to atoms conversion factor 3.5 moles x 6.02x1023 atoms = 2.12 x 1024 atoms 1 mole

Convert 18.06x1023 atoms to moles Atoms to moles conversion factor 18.06x1023 atoms x 1 mole = 3 moles 6.02x1023 atoms

Convert from moles to particles 2.7 moles of lithium 2.7 moles x 6.02x1023 particles 1 mole = 1.625 x 1024 atoms 1.8 moles of sodium chloride 1.8 moles x 6.02x1023 particles = 1.08 x 1024 molecules

Convert from moles to particles 5.3 moles of bromine 5.3 moles x 6.02x1023 particles 1 mole = 3.19 x 1024 atoms 4.7 moles of potassium oxide 4.7 moles x 6.02x1023 particles = 2.83 x 1024 molecules

BE CAREFUL WITH PARENTHESIS IN YOUR CALCULATOR! particles  moles 4.32 x 1024 atoms of calcium 4.32 x 1024 atoms x 1 mole 6.02 x 1023 atoms BE CAREFUL WITH PARENTHESIS IN YOUR CALCULATOR! = (4.32 x 10(24)) / (6.02 x 10(23)) = 7.18 moles of calcium

particles  moles 2.7 x 1020 atoms of copper 2.7 x 1020 atoms x 1 mole = (2.7 x 10(20)) / (6.02 x 10(23)) = 0.0004485 moles of copper =4.49 x 10-4 moles of copper

particles  moles 2.5 x 1024 molecules of sodium chloride 2.5 x 1024 atoms x 1 mole 6.02 x 1023 atoms =4.15 moles of sodium chloride 5.32 x 1023 molecules of calcium chloride 5.32 x 1023 atoms x 1 mole =0.88 moles of calcium chloride