Stoichiometry S1 - The Mole • Number of atoms equal to • 1 mole of anything = • 1 mole C = 6.022 x 10 23 C atoms = Calculate the number of iron atoms in a 4.48 mole sample of iron. S2 - Molar Mass • Mass in grams of one mole of the substance: Molar Mass of N = Molar Mass of H 2 O = Molar Mass of Ba(NO 3 ) 2 = Rank the following according to number of atoms (greatest to least): a) 107.9 g of silver (MM = 107.86 g/mol) b) 70.0 g of zinc (65.38 g/mol) c) 21.0 g of magnesium (24.305 g/mol) Consider separate 100.0 gram samples of each of the following: H 2 O (MM=18 g/mol) and CO 2 (MM=44 g/mol) Rank them from greatest to least number of oxygen atoms. Learning Objectives You should be able to: • identify the number of atoms present in a chemical formula • convert moles to number of particles/molecules/etc to moles
Stoichiometry S3 - Mass Percent • Mass percent of an element: • For iron in iron(III) oxide, (Fe 2 O 3 ): Consider separate 100.0 gram samples of each of the following: H 2 O, CO 2, N 2 O Rank them from highest to lowest percent oxygen bymass. S4 - Empirical and Molecular formula • Example: benzene • Empirical formula = • Molecular formula = Learning Objectives You should be able to: • define and calculate mass percent values from chemical formula • differentiate between molecular and empirical formulae • determine empirical and molecular formula from mass percent and combustion analysis data S5 - Empirical Formula • General rules for Empirical formula from starting from mass percentvalues: • Assume 100 g of total compound • Calc. # of moles of each element • Divide each value of moles by smallest value • If all values are whole numbers, the number for each element is thesubscript • If not, multiply by an integer to get whole numbers
Stoichiometry S7 - Empirical and molecular formulae The composition of adipic acid (precursor for industrial production of nylon) is 49.3% C, 6.9% H, and 43.8% O (by mass). The molar mass of the compound is about 146 g/mol. What is the empirical formula?
You've reached the end of your free preview.
Want to read all 9 pages?
- Fall '08