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Unformatted text preview: dewitt (aad777) – Homework 6 – sutcliffe – (52380) 1 This printout should have 20 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Avogadro’s number is really big. If you had 6.02 × 10 23 dollars, and could spend it at $1 billion (10 9 ) per second for the rest of your life (let’s say 80 years), approximately what percentage of your original money would you have left when you die? 1. 50% 2. 90% 3. 95% 4. 10% 5. 75% 6. 100% correct 7. 0% Explanation: 002 10.0 points Which one has the greatest number of atoms? 1. 3.05 moles of water 2. 3.05 moles of CH 4 correct 3. 3.05 moles of helium 4. 3.05 moles of argon 5. All have the same number of atoms Explanation: For 3.05 moles of water: ? atoms = 3 . 05 mol H 2 O × 6 . 02 × 10 23 molec 1 mol × 3 atoms 1 molecule = 5 . 51 × 10 24 atoms For 3.05 moles of CH 4 : ? atoms = 3 . 05 mol CH 4 × 6 . 02 × 10 23 molec 1 mol × 5 atoms 1 molecule = 9 . 18 × 10 24 atoms For 3.05 moles of helium: ? atoms = 3 . 05 mol He × 6 . 02 × 10 23 atoms 1 mol = 1 . 84 × 10 24 atoms For 3.5 moles of argon: ? atoms = 3 . 05 mol Ar × 6 . 02 × 10 23 atoms 1 mol = 1 . 84 × 10 24 atoms 003 10.0 points If one electron weighs 9 . × 10 − 28 grams, what is the mass of one mole of electrons? 1. 5 . × 10 − 24 grams 2. 9 . × 10 − 18 grams 3. 5 . × 10 − 23 grams 4. 1 . 5 × 10 − 51 grams 5. 5 . 4 × 10 − 4 grams correct Explanation: m = 9 . × 10 − 28 g We know one mole of electrons contains 6 . 022 × 10 23 electrons. Since we know the mass of an individual electron we can calcu late the mass of one mole of electrons. ? g/mol e − = 9 . × 10 − 28 g 1 e − × 6 . 022 × 10 23 e − 1 mol e − = 5 . 4 × 10 − 4 g/mol e − 004 10.0 points dewitt (aad777) – Homework 6 – sutcliffe – (52380) 2 What is the molar mass for fluoxetine (C 16 H 16 F 3 NO), also known as Prozac circlecopyrt R ? 1. 281.3 g/mol 2. 279.3 g/mol 3. 297.1 g/mol 4. 295.3 g/mol correct Explanation: MM C 16 H 16 F 3 NO = 16(12 . 011 g / mol) +16(1 . 0079 g / mol) + 3(18 . 9984 g / mol) +1(14 . 0067 g / mol) + 1(15 . 9994 g / mol) = 295 . 304 g / mol 005 10.0 points Calculate the density of propanol C 3 H 8 O if you know that there are 1 . 069 × 10 25 molecules of propanol in 1.35 L. 1. 1.27 g/mL 2. 1.23 g/mL 3. 0.789 g/mL correct 4. 0.0131 g/mL 5. 0.234 g/mL 6. 13.1 g/mL Explanation: n = 1 . 069 × 10 25 molec V = 1 . 35 L Density is g/mL, so we need to convert molecules propanol to g propanol and L to mL: ? g mL = 1 . 069 × 10 25 molec C 3 H 8 O 1 . 35 mL × 1 mol C 3 H 8 O 6 . 023 × 10 23 molec C 3 H 8 O × 60 g C 3 H 8 O 1 mol C 3 H 8 O × 1 L 1000 mL = 0 . 789 g / mL 006 10.0 points Calculate the number of ethanol molecules (CH 3 CH 2 OH) that would contain 164 grams of carbon....
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 Fall '07
 Fakhreddine/Lyon
 Chemistry, Mole, Mass, Molecule, mol, DeWitt

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