WA03_CHE-121-mar14

# WA03_CHE-121-mar14 - Written Assignment 3 Mass...

• Homework Help
• MegaIceJackal4529
• 2
• 100% (17) 17 out of 17 people found this document helpful

This preview shows pages 1–2. Sign up to view the full content.

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) (Reference: Chang 3.13) 5.1 mol x (6.022 x 10 23 atoms / 1 mol) = 3.07 x 10 24 atoms of S 2. How many moles of calcium (Ca) atoms are there in 77.4 g of Ca? (6 points) (Reference: Chang 3.15) 1 mol Ca = 40.078 g Ca 77.4 g Ca x (1 mol Ca / 40.078 g Ca) = 1.93 mol Ca 3. What is the mass in grams of 1.00 × 10 12 lead (Pb) atoms? (8 points) (Reference: Chang 3.19) (1.00 x 10 12 / 6.022 x 10 23 ) x 207.2 = 3.44 x 10 -10 4. Describe how you would determine the isotopic abundance of an element from its mass spectrum. (6 points) (Reference: Chang 3.32) Mass spectrometers can determine this information by measuring the amount of current generated from ions that are deflected via high-energy electron collisions. 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) Molar mass: [12.011 x 9 = 108.099] + [1.008 x 10 = 10.08] + 15.999 = 134.2g

This preview has intentionally blurred sections. Sign up to view the full version.

This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern