This document contains a chemistry lesson on molar mass. It defines molar mass as the sum of the atomic masses in a molecule. It provides examples of calculating the molar mass of different compounds by adding up the atomic masses of each element. The lesson concludes by having students practice calculating molar masses in groups and answering an exit slip with questions.

1. Launch: 11/24
 Grab you binder and immediately take a seat!
1. What is a mole?
2. What is Avogadro’s number?
3. How is a mole defined? (Hint: use the word carbon)

2. Launch 11/24
5. How many moles are there in 6g of carbon-12?
a. .5 moles
b. 1 mole
c. 2 moles
d. 12 moles

3. Announcements
 This is a really important week!
 Points end tomorrow
 Block 5 is in the lead
 Be engaged
 Be respectful

4. What is molar mass?
Mr. Heffner
11/24/09

5. What is a molar mass?
 Molar mass is…
 the sum of all of the atomic masses in a molecule
5
Atomic
B
Boron
mass 10.81

6. What is a molar mass?
 Molar mass is…
 the sum of the atomic masses in a molecule
H2O
Molar mass = mass of H + mass of H + mass of O
= 1.01 + 1.01 + 16.00
= 18.02 g/mol Units!

7. What is a molar mass?
 Molar mass is…
 the sum of the atomic masses in a molecule
NH3
Molar mass = mass of N + mass of H + mass of H + mass of H
= mass of N + 3X(mass of H)
= 14.01 + 3X(1.01)
= 14.01 + 3.03
= 17.04 g/mol Units!

8. What is a molar mass?
 Molar mass is…
 the sum of the atomic masses in a molecule
C2H2
Molar mass = mass of C + mass of C + mass of H + mass of H
= 2X(mass of C) + 2X(mass of H)
= 2X(12.01) + 2X(1.01)
= 24.02 + 2.02
= 26.04 g/mol Units!

9. What is a molar mass?
 Molar mass is…
 the sum of all of the atomic masses in a molecule
 a.k.a molecular mass or molecular weight
 basically, how much 1 mole of a molecule weighs

10. Whiteboards
 Work in pairs
 Trade-off marker every question
 You have 60 seconds to draw the answer
 Show all of your work!
 Don’t forget units!
 Lift board only when prompted

11. What is the molar mass of
of fluorine (F)?

12. What is the molecular mass
of O2?

13. What is the molecular mass
of CH4?

14. What is the molecular
weight of SOCl2?

15. What is the molar mass of
Ca(OH)2?

16. What is the molecular
weight of CH2COOH?

17. Practice Questions
 Practice question worksheet

18. Exit Slip
1. Molar mass is
a. a number with the units g/meters
b. the number of molecules in a gram of a substance
c. the sum of all of the atomic masses in a molecule
d. calculated by adding up the atomic numbers in a
molecule

19. Exit Slip
2. Molar mass is also called
a. molecular mass
b. molecular weight
c. molar weight
d. both a & b

20. Exit Slip
3. What is the molar mass of oxygen (O)?
a. 1.00 g/mol
b. 8.00 g/mol
c. 16.00 g/mol
d. 32.00 g/mol

21. Exit Slip
4. Which of the following show the correct way to
calculate the molecular weight of CH3OH?
a. 12.01 + 3 X (1.01) + 16.00
b. 12.01 + 4 X (1.01) + 16.00
c. 12.01 + 1.01 + 16.00
d. 6.00 + 1.00 + 8.00

22. Exit Slip
5. What is the molecular mass of Mg(OH)2
a. 24.31 g/mol
b. 41.32 g/mol
c. 58.33 g/mol
d. 100 g/mol

23. Homework
 Finish practice questions