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Chapter 3: Stoichiometry. Atomic Masses. Naturally occurring chlorine has the following properties 75.78% Cl-35 (34.969 amu) 24.22% Cl-37 (36.966 amu) Calculate the average atomic mass. Avogadro’s Number. The molecular formula for aspartame is C 14 H 18 N 2 O 5. (molar mass = 294.30 g/mol)
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Atomic Masses • Naturally occurring chlorine has the following properties • 75.78% Cl-35 (34.969 amu) • 24.22% Cl-37 (36.966 amu) • Calculate the average atomic mass
Avogadro’s Number • The molecular formula for aspartame is C14H18N2O5. (molar mass = 294.30 g/mol) • How many moles are present in 10.0 grams of aspartame? • Calculate the mass in grams of 1.56 moles of aspartame. • How many atoms of nitrogen are in 1.2 grams of aspartame? • What is the mass in grams of 1.0 x 109 molecules of aspartame?
Molar Mass and Percent Composition • What is the molar mass of C2H6O? • What is the mass percent of each atom in this molecule?
Empirical and Molecular Formulas • Adipic acid is an organic compound composed of 49.31% C, 43.79% O and the rest hydrogen. • Find the empirical formula • If the molar mass is 146.1 g/mol, what is the molecular formula?
Combustion Analysis • A combustion of 3.000 grams of acetylsalicyclic acid (made of carbon, hydrogen and oxygen) yields the following 1.200 grams of H2O and 6.60 grams of CO2. What is the empirical formula of this compound?
Balancing Chemical Equations • Balance the following__ NH3 + __ O2 __ NO + __ H2O __ Mg3N2 + __ H2SO4 __ MgSO4 + __ (NH4) 2SO4
Types of Equations • Combination: A + B CCaO(s) + H2O(l) Ca(OH)2(s) • Decomposition: C A + B2 KClO3(s) 2 KCl(s) + 3 O2 (g) • Combustion: CxHyOz + O2(g) CO2(g) + 4H2O(g)C3H8 + 5 O2(g) 3 CO2(g) + 4H2O(g)
Reaction Stoichiometry • K2PtCl4(aq) + 2 NH3(aq) Pt(NH3)2Cl2(s) + 2 KCl (aq)If you have 100. grams of K2PtCl4 with excess NH3 how much Pt(NH3)2Cl2 and KCl can we make?
Limiting Reactants • 6 Li(s) + N2(g) 2 Li3N(s)If 5.00 grams of each reactant undergoes a reaction with an 88.5% yield, how many grams of Li3N are obtained from the reaction?