chlorous acid phosphoric acid hydrobromic acid 36 Tro Chemistry A Molecular

# Chlorous acid phosphoric acid hydrobromic acid 36 tro

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chlorous acid phosphoric acid hydrobromic acid 36 Tro: Chemistry: A Molecular Approach, 2/e
2/1/2011 10 Formula Mass 37 Tro: Chemistry: A Molecular Approach, 2/e The mass of an individual molecule or formula unit head2right also known as molecular mass (MM)or molecular weight (MW) Sum of the masses of the atoms in a single molecule or formula unit (i.e., the whole = the sum of the parts!) mass of 1 molecule of H 2 O = 2(1.01 amu H) + 16.00 amu O = 18.02 amu Molar Mass 38 Tro: Chemistry: A Molecular Approach, 2/e The relative masses of molecules can be calculated from atomic masses Formula Mass = 1 molecule of H 2 O = 2(1.01 amu H) + 16.00 amu O = 18.02 amu 1 mole of H 2 O contains 2 moles of H and 1 mole of O so molar mass = 1 mole H 2 O = 2(1.01 g H) + 16.00 g O = 18.02 g head2right the Molar Mass of H 2 O is 18.02 g/mole Converting grams to moles How many moles are in 50.0 g of PbO 2 ? (Pb = 207.2, O = 16.00) 39 Tro: Chemistry: A Molecular Approach, 2/e How many formula units are in 50.0 g of PbO 2 ? (PbO 2 = 239.2) 40 Tro: Chemistry: A Molecular Approach, 2/e
2/1/2011 11 What is the mass of 4.78 x 10 24 NO 2 molecules? 41 Tro: Chemistry: A Molecular Approach, 2/e Percent Composition 42 Tro: Chemistry: A Molecular Approach, 2/e Percentage (by mass) of each element in a compound; sometimes called “mass %” Can be determined from 1. the formula of the compound 2. the experimental mass analysis of the compound (Note that the %s may not always total to exactly 100% due to rounding) Determine the mass % composition of the following: CaCl 2 (Ca = 40.08, Cl = 35.45) 43 Tro: Chemistry: A Molecular Approach, 2/e Benzaldehyde is 79.2% carbon. What mass of benzaldehyde contains 19.8 g of C? 44 Tro: Chemistry: A Molecular Approach, 2/e
2/1/2011 12 Conversion Factors in Chemical Formulas Chemical formulas have inherent in them relationships between : head2right numbers of atoms and molecules head2right or moles of atoms and molecules These relationships can be used to convert between amounts of constituent elements and molecules, like percent composition 45 Tro: Chemistry: A Molecular Approach, 2/e How many grams of sodium are in 6.2 g of NaCl? (Na = 22.99; Cl = 35.45) 46 Tro: Chemistry: A Molecular Approach, 2/e Empirical Formula Simplest,whole-number ratio of the atoms of elements in a compound Can be determined from elemental analysis combustion analysis percent composition 47 Tro: Chemistry: A Molecular Approach, 2/e Finding an Empirical Formula 48 Tro: Chemistry: A Molecular Approach, 2/e 1. Convert the percentages to grams a) assume you start with 100 g of the compound b) skip if already grams 2. Convert grams to moles a) use molar mass of each element 3. Write a pseudoformula using moles as subscripts 4. Divide all by smallest number of moles a) if result is within 0.1 of whole number, round to whole number 5. Multiply all mole ratios by number to make all whole numbers

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• Fall '08
• LEMASTER
• Chemistry, Mole, pH, Molecule, Ion, Chemical bond, Molecular Formulas, Molecular Approach