1. Convert 25mol of N2O2 into grams.
Bell Ringer Jan. 13
Convert 25mol of N2O2 into grams.
Convert 625 grams of Selenium into moles.

3. Important Note:
Percent composition: the percentage by mass of each element in a compound.

4. Our problem for the day…
What is the percentage composition of ibuprofen??

5. Chex Mix! First Things First…
Your bag of Chex mix contains 15 pretzels and 3 rye crackers and a whole lot of Chex. What is the percent of pretzels in the mixture?

6. What is the percentage Composition of Pretzels in my mixture??
Mass of Pretzels
X 100 = mass % of Pretzels
Total Mass of Chex Mix
We can use this same idea to calculate the mass % of elements in a compound…consider CaCl2

7. Percent composition
The mass percentage of an element in a compound is the same regardless of the sample’s size

8. Percent Composition % element in compound X 100 =
Mass of element in 1 mole of compound
% element in compound
X 100 =
Molar Mass of Compound

9. Class Example: What I write…you write
Calculate the percent composition by mass of each element in a sample of calcium chloride.

10. Find the percent composition of ibuprofen, C13H18O2
Find the percent composition of ibuprofen, C13H18O2. Record answers to the nearest hundredth.

14. What is the percent composition and empirical formula for N2O4?
Exit Ticket Jan. 13
What is the percent composition and empirical formula for N2O4?