chm115_lecture3

chm115_lecture3 - 3-1Chemistry 115Lecture 3 OutlineChapter...

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Unformatted text preview: 3-1Chemistry 115Lecture 3 OutlineChapter 4Chapter 11gm - mol - molec. ConversionsIdeal Gas Law, STPBalancing Chemical ReactionsPartial PressureStoichiometryLimiting ReagentsRecitation:Chapters 4 and 11 review3-2The Mole - What is a mole?3-3The Mole•Since 6.022×1023 ×12 amu = 12g, 6.022×1023amu = 1g•The mole (mol) is a counting unit for objects-atoms, molecules, ions, etc.•Avogadro’s number is chosen so that 1 mole of 12C atoms has a mass of exactly 12 g.•A mole represents 6.0221367×1023objects. This is known as Avogadro’s number.3-43-5Average Atomic MassWhy does atomic atomic mass of carbon = 12.011 amu?We average the masses of isotopes to give relative atomic masses:Naturally occurring C consists of 98.892% 12C (12 amu) and 1.108% 13C (13.00335 amu).The average mass of C is therefore:(0.98892)(12 amu) + (0.0108)(13.00335) = 12.011 amu.Atomic weight(AW) is also known as average atomic massAW are listed on the periodic table.3-6Molar massThe molar massof a substance = mass of 1 mole ingrams.It is numericallyequal to the formula weight in amu.Avg. mass of 1 C atom = 12.011amuMass of 1 mole of C = 12.011 gMass of 1 H2O molecule = 18.015 amuMass of 1 mol of H2O = 18.015 gMultiply by Avogado’s number to get #atoms: # O atoms in 18g H2O? 18g = 1 mol = 2 x 6.0x1023O molar mass of O plus2x the molar mass of HIf the moles are other than one, how do I calculate the mass?3-7MW = g/mol6.022 x 1023 molec/moleGramsMoles#moleculesgmolmolecBe familiar with the following conversion:Ex: CO2GramsgMolesmol#moleculesmolec88 g CO22 mol CO21.2 x 1024molec CO264 g O4 mol O2.4 x 1024atoms OCQ3-8Balancing Chemical EquationsA balanced chemical equation has the same type and number of atoms in the reactants as in the productsFuel Cell Rxn3-9Stoichiometry(Chemical Equations)Mass is conserved in a chemical reaction.The quantitative nature of chemical formulas and reactions is called stoichiometry.Chemical equations give a description of a chemical reaction.reactants 2H2+ O22H2O / productsTwo types of numbers:numbers in front of the chemical formulas (stoichiometric coefficents) andnumbers in the formulas(they appear as subscripts)....
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chm115_lecture3 - 3-1Chemistry 115Lecture 3 OutlineChapter...

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