Chap 3 Sec 1-3

# Chap 3 Sec 1-3 - 3.1 The Mole Term like dozen or ream but...

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Chap 3 Sec 1 to 3.doc 10/09 Page 1 3.1 The Mole Term like dozen or ream but huge! 1 mole of anything = 6.022 x 10 23 of that thing It is usually used for atoms, molecules and other compounds (ionic compounds often use the term “formula units” but for the purposes of # of moles and amount of weight we will loosely stick them under the term molecules also. An amu (atomic mass unit) is used for individual atomic masses, but we will use the same value for a mole of atoms. The average weight of a hydrogen atom is 1.008 amu . The weight of 1 mole of hydrogen atoms is 1.008 g or 1.008 g/mole . Molecular Mass = Molecular Weight = Molar Mass A substance’s molar mass (molecular weight) is the mass in grams of one mole of the compound. CO 2 = 44.01 grams per mole To find the molar mass add up the average weight of the atoms. Example: Al 2 (CO 3 ) 3 Keep 4 sf from periodic table (or more) to calculate. 2 Al = 2 x 26.98 = 53.96 3 C = 3 x 12.01 = 36.03 9 O = 9 x 16.0 0 = 144. 0 0 233.99 234.0 g = 1 mole of Al 2 (CO 3 )

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Chap 3 Sec 1 to 3.doc 10/09 Page 2 Conversions 1) Example: 8.46 g B = ? moles From periodic table - 8.46 g B x 1 mole 10.81 g = 0.783 moles of B OR AW = g moles therefore moles = g AW AW = 8.46 g 10.81 g mole = 0.783 moles How many grams of Pb are in 0.038 moles of Pb? ( M = 207.19 g/mole) WORK THIS PROBLEM How many moles are in 1.36 grams of Al 2 (CO 3 ) 3 ?
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Chap 3 Sec 1-3 - 3.1 The Mole Term like dozen or ream but...

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