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Meet the Mole. The Mole. Avogadro's hypothesis suggests that we can compare the number of molecules in a gas sample. Even though we can’t see them. A standard number of molecules is called a mole (mol). A mole always contains the same number of molecules. A mole is 6.02 x 10 23
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The Mole • Avogadro's hypothesis suggests that we can compare the number of molecules in a gas sample. • Even though we can’t see them. • A standard number of molecules is called a mole (mol). • A mole always contains the same number of molecules. A mole is 6.02 x 1023 • A mole of CO2 contains the same number of molecules as O2molecules
Molar Mass • The # of molecules in a mole maybe the same, but the mass will be different. • This is called a molar mass. • Molar is based on the mass of Carbon-12. • Mass recorded on the Periodic Table takes into account all of the naturally occurring isotopes of the atom and their relative abundance. • Has units of g/mole
What does the mole allow us to do? • The mole allows for the measurement of really small particles. • 1 mole = 6.02 x 1023 (Avogadro’s Number) • The mole takes into account: # of atoms in a chemical formula, mass of an individual atom, mass of a chemical compound, and # of molecules in a compound
Determine the number of atoms in the following chemical formula • Ex. CaCl2 = 1 Ca atom, 2 Cl atoms • NaCl KMnO4 • H2SO4 Fe2O3 • KNO3 K2SO3 • C2H6 Al2(SO4)3 • Ba(OH)2 HgCl2 • NH4Br Mg(C2H3O2)2 • Cu(NO3)2 NaC2H3O2
Calculate the mass of each of the following compounds • Ex. KCl 39.10 g/mol + 35.45 g/mol = 74.55 g/mol • NaCl KMnO4 • H2SO4 Fe2O3 • KNO3 K2SO3 • Al2(SO4)3 Ba(OH)2 • NH4Br Mg(C2H3O2)2 • Cu(NO3)2 NaC2H3O2
Calculate the moles in each compound • How many moles in 60 grams of NaCl? • How many moles in 100 grams of H2SO4? • How many moles in 60 grams of C2H6? • How many moles in 60 grams of Mg(C2H3O2)2? • How many moles in 60 grams of Al2(SO4)3 ? • How many moles in 60 grams of NH4Br ?
Avogadro’s # put to work… • Avogadro’s # (1 mole = 6.02 x 1023 ) is used to convert between moles of a substance and the number of molecules, atoms, particles. • One can also convert between mass of a substance and number of molecules, atoms, particles. • Convert mass to moles first
Calculate the # of molecules in each compound • How many molecules in 3 moles of Fe2O3? • How many moles in 9.03 x 1023 atoms of Hg? • How many molecules in 5 moles of NH4Br? • How many moles in 3.01 x 1023 atoms of HgCl2 ?
Now for some practice… • Calculate the molar mass of oxygen
Now for some practice… • How many dozen are 60 eggs? • How many eggs are in 13 dozen? • What is the mass of 2.50 moles of oxygen? • How many moles are in 4.00 g oxygen? • What is the mass of 2.50 mol carbon dioxide? • How many moles are in 4.00 g carbon dioxide?