1. % Composition, Empirical and Molecular Formula Mrs. Wilson
Monday and Tuesday 12-01
% Composition, Empirical and Molecular Formula
Mrs. Wilson

2. Daily Quiz
Feel free to use a white laminated periodic table. No other aids may be used, other than your brain.
Use your green sheet.

3. Objectives
Calculate % composition of an element in a compound.
Use data to calculate the empirical formula of a compound.
Use data to calculate the molecular formula of a compound.
Homework: Hwk 3.8 due T (for Daily Quiz); Major Quiz 3.2 on Thurs Have your hair tied back and closed toe shoes for Friday. Unit 3 Exam on Thurs

4. Why care about knowing the formula of a compound?
To help identify it – each compound has a unique formula.
To identify its properties – so we can use it for various applications (medicines, etc).
The first step in determining the formula of a compound is to figure out its percent composition.

5. by mass
mass
elements
molar masses

6. compounds
** Law of Definite Proportions: A chemical compound – no matter where you find it or the mass of the sample – always contains the same percentages of each element by mass.

8. Group
% Sugar in Gum
Sources of error:

9. formula
molar mass
the element
100
the correct %

10. Work out the rest of the % composition problems on pg. 31
Work out the rest of the % composition problems on pg Check your answers here.
Example 2 – % Cu, % S, % oxygen (Copper (I) sulfate is the better O source) Practice a) 40.04% Ca, 12.00% C, 47.96% O Practice b) 16.38% Mg, 18.89% N, 64.73% O Practice c) Dihydrogen monoxide

11. reduced
actual
identical
whole-number

12. the subscripts simplest formula empirical molecular molecular 100
molar mass
smallest
the subscripts

14. Answer: SnCl2I2

15. empirical formula
molar mass
molar mass
Divide
Multiply

17. Molecular formula: C8H18

18. Kahoot!
kahoot.it

19. 3-2-1
On your index card, write:
3 facts you have learned so far in class about types of reactions, as well as redox reactions, and feel as if you really understand it.
2 facts you know ARE true about types of reactions and redox reactions, but feel shaky on.
1 question you still have about reaction types and redox reactions.