WA03_CHE-121-mar14

# WA03_CHE-121-mar14 - Thomas Edison State College General...

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Thomas Edison State College General Chemistry I with Labs (CHE-121) Section no.: OL009 Semester and year: May 2015 Written Assignment 3: Mass Relationships for Compounds Answer all assigned questions and problems, and show all work. 1. How many atoms are there in 5.10 moles of sulfur (S)? (6 points) (5.10)(6.02 x 10 23 atoms/mol) = 3.07 x 10 24 atoms (Reference: Chang 3.13) 2. How many moles of calcium (Ca) atoms are there in 77.4 g of Ca? (6 points) 77.4g Ca x 1 mole Ca/40.08g Ca = 1.931 mole Ca (Reference: Chang 3.15) 3. What is the mass in grams of 1.00 × 10 12 lead (Pb) atoms? (8 points) (1.00 x 10 12 )(207.2)/6.02 x 10 23 = 3.44 x 10 -10 (Reference: Chang 3.19) 4. Describe how you would determine the isotopic abundance of an element from its mass spectrum. (6 points) Calculate relative atomic mass and that will determine number of isotopes for the element. (Reference: Chang 3.32) 5. Cinnamic alcohol is used mainly in perfumery, particularly in soaps and cosmetics. Its molecular formula is C 9 H 10 O. a. Calculate the percent composition by mass of C, H, and O in cinnamic alcohol. (8 points) 9 x 12g/mole = 108.0g C 1 Copyright © 2014 by Thomas Edison State College. All rights reserved.

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10 x 1.01g/mole = 10.1g H
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