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Chem 161-2010 lectur - CHEMISTRY 161-2010 LECTURE 4 ANNOUNCEMENTS E-MAIL ATTENDANCE (inthefrontofthe auditorium)(i.e,ifyouhaventbeen HOURLY EXAM

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CHEMISTRY 161-2010 LECTURE 4 ANNOUNCEMENTS E-MAIL Don’t let your mailboxes get full. ATTENDANCE Add your name and e-mail address to my list (in the front of the  auditorium) if it isn’t already listed (i.e., if you haven’t been  receiving e-mail from me). HOURLY EXAM Exam I: Wednesday, Sept. 22, 9:40 – 11:00 PM, chapters 1 to 3.8 CATCH-UP Many students missed Friday’s lecture due to religious observance. I’ll stay late on Tuesday to redo Friday’s lecture, if enough students are interested. LECTURE NOTES Please copy these notes and bring to class. Chem 161-2010 Lecture 4 1
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Chapter 3: • MOLECULAR AND FORMULA MASSES Chem 161-2010 Lecture 4 2
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PART II - CHAPTER 3 MOLES Note to ET: Define moles Chem 161-2010 Lecture 4 3 MOLE
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ORIGIN OF “MOLES” Chemists found that: Hydrogen + Oxygen Water 2.0g 16.0g 18.0g As time went on it was determined that these quantities were equivalent to: Hydrogen + Oxygen Water 12.04 x 10 23 atoms 6.022 x 10 23 atoms 6.022 x 10 23 molecules = 2:1 ratio of H atoms to O atoms = H 2 O Chemists frequently work with atoms and molecules. Mass is only used to calculate the number of atoms and molecules. Although quantities such as 2.0g, 16.0g or 18.0g are convenient to work with, the corresponding number of atoms and molecules (12.04 x 10 23 atoms, 6.02 x 10 23 atoms or 6.02 x 10 23 molecules) is not convenient. Inconvenient Convenient 12 eggs 1 dozen eggs (or 1 doz anything) 144 buttons 1 gross of buttons 500 sheets of paper 1 ream of paper 6.022 x 10 23 atoms* 1 mole of atoms (or anything) * This is the number of atoms in 12g of 12 C; 12 C was arbitrarily picked as the reference. Now we have convenient numbers for atoms/molecules and convenient numbers for masses: Hydrogen + Oxygen Water 2.0g 16.0g 18.0g 2 mol of atoms 1 mol of atoms 1 mol of molecules (12.044x10 23 atom) (6.022x10 23 atom) (6.022x10 23 atom) Chem 161-2010 Lecture 4 4
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ET note: Not everything goes through moles, e.g., volume to grams, grams to volume, atoms to molecules, molecules to atoms. ZUMDAHL 6
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This note was uploaded on 03/30/2011 for the course CHEM 161 taught by Professor Vacillian during the Spring '08 term at Rutgers.

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Chem 161-2010 lectur - CHEMISTRY 161-2010 LECTURE 4 ANNOUNCEMENTS E-MAIL ATTENDANCE (inthefrontofthe auditorium)(i.e,ifyouhaventbeen HOURLY EXAM

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