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Day 3 Chem 105 f 2010

Day 3 Chem 105 f 2010 - Chem Chem 105 105 Friendly reminder...

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Unformatted text preview: Chem Chem 105 105 Friendly reminder: Friday is open seating day—AND CANDY DAY! 1 If you have questions before or after class, please address them to the Peer Mentors first. Answers to many of the Answers Problems in the text are found in the text. For Practice Exercises (in the chapter) , the answer is with the problem. For Exercises Exercises (at the end of the chapter), (at the answer is in the back of the text. the John D. Lamb, BYU Educational thought for the day: “It is imperative that we take It advantage of the opportunity to learn. The Lord has said concerning us of this Church that He expects us to study and learn. I know of no other church that has scripture instructing its people to pursue secular knowledge as well as spiritual knowledge.” Pres. Hinckley Pres. 2 John D. Lamb, BYU Sound advice Look at the Look calendar daily! calendar Text on Reserve Brown, et al., 11th ed. HBLL Reserve Library 3 John D. Lamb, BYU How much time should you How expect to spend on this class? expect Depends on your starting point. Had this chemistry before? Yes? Start here No? Start here Who needs to spend more time? 4 John D. Lamb, BYU And now… A little sage advice about grades 5 John D. Lamb, BYU Survey of Survey freshmen 2006 2006 What were most of your high school grades? What do you expect most of your grades will be at this college during the coming year? 100% 90% 80% 70% 66% 60% 50% 40% 33% 30% 20% 10% 1% 0% C Grades not used 0% A B high school college John D. Lamb, BYU Chem 105 Chem 2005 2005 What were most of your high school grades? What do you expect most of your grades will be at this college during the coming year? 100% 90% 80% 70% 66% 60% 50% 40% 33% 30% 20% 10% 1% 0% C Grades not used D E 0% A B high school college John D. Lamb, BYU During your last year of high school, about how many hours did you spend in a typical 7-day week preparing for class? time spent preparing for class During the coming school year, about how many hours do you think you will spend in a typical 7in typical 7-day week day week preparing for classes? University University recommended for 15 credits 30-45 30-45 60% 48% 50% 40% 30% This class 812 hr/week 33% 20% 9% 10% 0% 9% 0% 0 hours 10 or less 11-20 hours high school 21-30 hours More than 30 hours college John D. Lamb, BYU 9 John D. Lamb, BYU Virtual Chem Virtual Lab Lab Why: experience first-hand how the “quantum” model of charge was tested When: any time after now Will you be tested on this? Use the Instruction/Worksheet I prepared—on BB—NOT the Workbook that came in your MediaPack on your honor to actually DO the lab 10 John D. Lamb, BYU from Millikan/Fletcher MODEL: electron is a particle— quantized negative charge comes in indivisible packets (quanta) 1.602176462 x 10-19 coulomb (from back page of book) Tesla coil Optional: Try the Millikan Experiment in Virtual Chem Lab—see found on BB 11 John D. Lamb, BYU Did you remember? Set your IClicker frequency to “CC” as soon as you sit down 12 John D. Lamb, BYU Survey: participation only Have you done the Math Have Diagnostic Quiz on BB? a) yeah b) nay c) Huh? 13 Math Review Sessions: Math TBA by email. TBA John D. Lamb, BYU Dimensional Analysis If I have 360 donuts, how If many dozens do I have? a) b) c) g) 14 30 36 12 just enough to feed one hungry Chem 105 student Do a roadmap. John D. Lamb, BYU Example: If I have 69 g of sodium, If how many sodium atoms do I have? do ☺answer in either mol or # --unless specified --unless 15 John D. Lamb, BYU If I have 3.6 x 1028 atoms, how many moles (of atoms) do I have? a) b) c) d) 16 3.0 x 103 mol 36 mol 6.0 x 10-3 mol 60,000 mol John D. Lamb, BYU Learn to do calculations Learn without a calculator without Convert everything to scientific notation. Process the exponents separately. Good preparation for GRE, MCAT, DAT, etc. 17 John D. Lamb, BYU Let’s use dimensional Let’s analysis analysis Stars: 100 billion galaxies with 100 billion Stars: stars stars Sand: 100,000 km of beach: 100 m wide & Sand: 1 m deep deep 10 mL weigh 15.8 g 30 grains weigh 0.0084 g NOTE: 1 mL = 1 cm3 18 John D. Lamb, BYU Question Suggestion Write your questions down and bring them to your PM or to me during office hours (see syllabus) Or make an appointment— email me. 19 John D. Lamb, BYU DENSITY REVIEW from High School characteristic of a material changes slightly with temperature depends on weight of each atom (Pb and C from last time) 20 mass volume also depends on how also closely atoms are packed packed Styrofoam Brick John D. Lamb, BYU He balloon versus sulfur He hexafluoride balloon? hexafluoride • same number of particles (atoms/molecules) Which is denser? Why? 21 John D. Lamb, BYU Pb & C: Why do the two Pb samples have such different weights when they are about the same size? the (a) the lighter sample contains fewer atoms that have bigger diameters (b) the heavier sample contains more atoms (c) each atom in the lighter sample contains He (d) the atomic weight of C is smaller than that of Pb 22 John D. Lamb, BYU What is the density of water? a) b) c) d) 23 1.00 lb/mL 50.0 g/m3 1.00 g/cm3 5.00 g/L If you didn’t If know the answer, could you reason it out? out? John D. Lamb, BYU The density of water is 1.00 g/cm3. What What is the density in lb/m3? (1 lb=454 g) is (1 a) b) c) d) 24 2.20 x 106 lb/m3 2.20 x 103 lb/m3 4.54 x 106 lb/m3 3.72 x 104 lb/m3 John D. Lamb, BYU 25 John D. Lamb, BYU for atoms: What is the mass in g of 1 million What chlorine atoms to 3 significant digits? chlorine a) b) c) d) 26 6.95 x 10-6 g 2.13 x 103 g 5.89 x 10-17 g 3.85 x 10-67 g Same question for 1 million Cl- ions… John D. Lamb, BYU Molecular Formulas & Weights What does it mean? H2 What does a mole of H2 weigh? weigh? H2O ? You try CH4 27 Molecular weight vs atomic Molecular weight weight John D. Lamb, BYU NOTE: if there are 10 p/molecule, then NOTE: there are 10 mole of p/mole of molecules How many moles of protons are in 2.0 g How of CH4 ? (e.g., in a typical balloon) of (e.g., a) b) c) d) 28 5.0 mol 5/4 mol 3.0 x 1023 mol 5.0 x 10-23 mol John D. Lamb, BYU Example: Use dimensional analysis Now your turn! How How How many moles of H atoms are in 8.0 g How many moles of protons are in 8.0 of f CH oof g f CH4?4? o a) b) c) d) 29 2.0 mol 0.50 mol 3.0 x 1023 mol 5.0 x 10-23 mol John D. Lamb, BYU This week “Training wheels” – get our system working Tools needed to understand “quantitative” science Review for most students—if not? PM’s Technology in perspective 30 John D. Lamb, BYU Closing Thoughts: If you don’t complete all the problems in the DLC part of each practice sheet, you need to complete them at home. You need to do this to prepare for the exams! If you are not completing the ChemTutor and reading exercises before class, you are establishing a failing behavior pattern!! If you ARE doing all that is recommended, you’re on the road to success. 31 John D. Lamb, BYU Buona festa per Buona Labor Day! Labor 32 John D. Lamb, BYU Example Diamond has a density of 3.513 g/cm3. The mass of diamonds is often measured in carats, 1 carat equaling 0.200 g. What is the volume (in cc’s) of a 1.50carat diamond? 33 John D. Lamb, BYU ...
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