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Learn about the concept of the mole and how it measures the number of particles in different samples in chemistry. Discover how moles help determine reactions using proportions with examples provided.
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Moles Part 1 – Particles Aim CE3: How many different measures is a mole?
Intro to the Mole, the Chemist’s Dozen A mole - a given number of particles A pair of shoes = 2 items A dozen roses = 12 items A mole of water = 6.02 x 1023 items or particles
A mole measures the number of particles in different samples 1 mole of iron (Fe) has 6.02 x 1023 atoms 2 moles of iron has how many atoms? 2 x (6.02 x 1023) = 1.204 x 1024 atoms 1 mole of sulfur (S) has 6.02 x 1023 atoms How many moles of sulfur are in 8 moles? 2 x (6.02 x 1023) = 1.204 x 1024 atoms 1 mole of water has 6.02 x 1023 molecules 5 moles of water has how many molecules? 5 x (6.02 x 1023) = 3.01 x 1024 molecules
1 mole of water has 6.02 x 1023 molecules How many ATOMS are in 1 mole of water? This can be answered using proportions H2O = 3 atoms for each molecule 3 atoms = X moles atoms 1 molecule 1 mole molecules X =3 moles atoms How many atoms are in 3 moles of atoms? 3 moles atoms = X atoms 1 mole molecules 6.02 x 1023 molecules X = 3x(6.02 x 1023) =18.06 x 1023 atoms
Knowing that all moles have the same number of particles is important in chemical reactions It allows the chemist to determine how many particles will be reacting Example: 2 H2 + O2 2 H2O The equation tells us that 2 molecules of H2 will react with 1 molecule of O2 to make 2 molecules of water It ALSO tells us 2 moles H2 and 1 mole O2 will produce 2 moles of water Remember, 1 mole = 6.02 x 1023 particles! That’s a lot of molecules in this reaction!
Practice • How many atoms are in a 2.00 mole sample of aluminum? • How many molecules are in a 0.500 mole sample of ammonia? • How many atoms are in a 1.00 mole sample of the compound hydrogen bromide (HBr)? • How many ions are in a 4.00 mole sample of sodium chloride (NaCl)?