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HW7 - padilla(tp5647 Homework 7 Sutclie(53770 This...

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padilla (tp5647) – Homework 7 – Sutcliffe – (53770) 1 This print-out should have 25 questions. Multiple-choice 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. 100% correct 2. 50% 3. 90% 4. 0% 5. 95% 6. 75% 7. 10% Explanation: 002 10.0 points Which one has the greatest number of atoms? 1. 3.05 moles of CH 4 correct 2. 3.05 moles of argon 3. 3.05 moles of water 4. 3.05 moles of helium 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 . 0 × 10 28 grams, what is the mass of one mole of electrons? 1. 5 . 0 × 10 24 grams 2. 5 . 0 × 10 23 grams 3. 5 . 4 × 10 4 grams correct 4. 1 . 5 × 10 51 grams 5. 9 . 0 × 10 18 grams Explanation: m = 9 . 0 × 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 . 0 × 10 28 g 1 e × 6 . 022 × 10 23 e 1 mol e = 5 . 4 × 10 4 g/mol e 004 10.0 points What is the molar mass for fluoxetine (C 16 H 16 F 3 NO), also known as Prozac circlecopyrt R ?
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padilla (tp5647) – Homework 7 – Sutcliffe – (53770) 2 1. 281.3 g/mol 2. 297.1 g/mol 3. 279.3 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 This is ATOMS of bromine, for this question. How many moles of bromine are in 2.60 × 10 2 grams of bromine? 1. 48.6 mol 2. 3.25 mol correct 3. 2.29 mol 4. 79.9 mol 5. 10.5 mol 6. 0.308 mol 7. 0.0152 mol Explanation: m Br = 2.60 × 10 2 g ? mol Br = ( 2 . 60 × 10 2 g Br ) × 1 mol Br 79 . 9 g Br = 3 . 25 mol Br 006 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. 13.1 g/mL 2. 1.23 g/mL 3. 0.0131 g/mL 4. 0.789 g/mL correct 5. 1.27 g/mL 6. 0.234 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 007 10.0 points Calculate the number of ethanol molecules (CH 3 CH 2 OH) that would contain 164 grams of carbon. 1. 5.93 × 10 26 molec 2. 9.94 × 10 25 molec 3. 4.11 × 10 24 molec correct 4. 1.89 × 10 26 molec 5. 1.65 × 10 25 molec 6. 8.28 × 10 24 molec 7. 3.73 × 10 25 molec Explanation:
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padilla (tp5647) – Homework 7 – Sutcliffe – (53770) 3 m C = 164 g ? molec = 164 g C × 1 mol C 12 g C × 1 mol C 2 H 6 O 2 mol C × 6 . 022 × 10 23 molec 1 mol C 2 H 6 O = 4 . 11 × 10 24 molec 008 10.0 points How many moles are in 63.0 g of (NH
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