# Ap Chemistry Notes Unit 2

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I. Compounds A. Weight of Compounds (The Mole again!) molar mass – the amount 1.0000 _____________ of a substance weighs. Or the amount of ___________________________________ particles of the substance weighs. 1 mole hydrogen = _____________ g = _______________________ atoms 1 mole sodium = _____________ g = _____________________ atoms 1 mole chlorine = _____________ g = ____________________ atoms 1 mole sodium chloride = ________________ g = ____________________________ formula units 1 mole glucose = __________________g = ____________________________ molecules Example Problem 1. A can of artificially sweetened soft drink may contain 70.0 mg of aspartame, or NutraSweet@, C14H18N2O5. (a)Calculate the number of moles of aspartame in the soft drink. (b) Calculate the number of molecules of aspartame in the soft drink and the number of atoms of carbon. (c) Calculate the mass in grams and in amu of one molecule of aspartame. Law of constant (definite) composition - any sample of a pure compound always consists of the same elements combined in the same proportions by mass B. Percent Composition Example Problem 2. What is the weight percent of each element in ammonium sulfate? C. Empirical and Molecular Formulas 1. Empirical Formula - shows the number of atoms in the smallest possible ratio a. may be calculated from percent composition data b. may or may not show the true number of atoms of each kind in the molecule 2. Molecular Formula - shows the true