So what unit do chemists use to count particles?
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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
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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 marshmallows would cover the US to a depth of 650 miles
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• 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
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Recall the Law of Conservation of Mass
Mass of reactants = mass of productsMass of starting substances = mass of ending substances
2 hydrogen atoms + 1 oxygen atom 1 water molecule
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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
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Moles ↔ Particles Conversion
ParticlesAtoms, molecules
x 6.02 x 1023
÷ 6.02 x 1023
Moles
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Convert 3.5 moles to atoms
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Convert 18.06x1023 atoms to moles
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Convert from moles to particles• 2.7 moles of lithium
• 1.8 moles of sodium chloride
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Convert from moles to particles• 5.3 moles of bromine
• 4.7 moles of potassium oxide
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particles moles
• 4.32 x 1024 atoms of calcium
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particles moles
• 2.7 x 1020 atoms of copper
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particles moles
• 2.5 x 1024 molecules of sodium chloride
• 5.32 x 1023 molecules of calcium chloride
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You try these…
• 25 moles to particles
• 4.08 x 104 particles to moles
• 0.002 moles to particles
• 2.3 x 1016 particles
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HomeworkComplete on another sheet of
paper showing your work!
• Moles to particles
2.7 moles
1.8 moles
5.3 moles
4.7 moles
• Particles to moles
4.32 X 1024
2.70 X 1020
2.50 X 1024
5.32 X 1023