1. Moles, Avogadro’s Number and Molar Mass
Converting moles to molecules, atoms, and particles

2. Can anyone define the term mole?

3. Mole SI unit used to measure the amount of a substance
equal to 6.02 x 1023 atoms, molecules, or particles
Avogadro’s number
Abbreviated by mol

4. Avogadro’s Number 6.02 X 1023 Used to count extremely small particles
Named in honor of Italian physicist Amedeo Avogardo
Determined the volume of one mole of a gas

5. Conversions

6. Mole  Molecules, Atoms, or Particles
In order to convert moles to molecules atoms, or particles, you have to MULTIPLY the number of moles by Avogadro’s number (6.02 x 1023)
Example: How many atoms are there in 4.0 moles?

7. How many atoms are there in 4.0 moles?
Moles  Atoms…MULTIPLY BY AVOGADRO’S NUMBER
2.4 x 1024 atoms

8. Molecules, Atoms, or Particles  Moles
In order to convert molecules, atoms, or particles to moles, you have to DIVIDE the number of moles by Avogadro’s number (6.02 x 1023)
Example: How many moles are there in 7.14 x 1023 molecules?

9. How many moles are there in 7.14 x 1023 molecules?
Molecules  Moles…DIVIDE BY AVOGADRO’S NUMBER
1.19 moles

10. Practice

11. How many molecules are there in 3.5 moles?
Moles  Molecules…MULTIPLY BY AVOGADRO’S NUMBER
2.11 x 1024 molecules

12. How many particles are there in 9.6 moles?
Moles  Particles…MULTIPLY BY AVOGADRO’S NUMBER
5.78 x 1024 particles

13. How many moles are there in 5.75 x 1024 atoms?
Atoms  Moles…DIVIDE BY AVOGADRO’S NUMBER
9.55 moles

14. How many moles are there in 3.58 x 1023 particles?
Molecules  Moles…DIVIDE BY AVOGADRO’S NUMBER
0.59 moles

15. End Day 1

16. Molar Mass

17. Molar Mass the mass in grams of one mole of any pure substance
In other words, the molar mass of any element is equivalent to the atomic mass of that element
in units of grams per mole; g/mol

18. Calculating Molar Mass
- To calculate the molar mass of a substance, you add the atomic mass of every element in the compound
The total atomic mass is the molar mass of the substance.

19. What is the molar mass of N?
Example
What is the molar mass of N?
Step 1: determine the atomic mass
N: 14
Step 2: add units
g/mol
molar mass = 14 g/mol

20. What is the molar mass of CO2?
Example
What is the molar mass of CO2?
Step 1: determine the mass of each element
C: 12
O: 16 X 2
Step 2: add the masses to get the total atomic mass
=44
Step 3: add units
g/mol
Molar mass = 44 g/mol

21. Practice What is the molar mass of NaCl?
58.5 g/mol
What is the molar mass of H3O?
19 g/mol
What is the molar mass of H2SO4?
98 g/mol

22. END

23. Mole  Gram Conversions

24. Review
Mole
SI unit used to measure the amount of a substance
Abbreviate by mol
Molar mass
total atomic mass of every element in the compound
Units: g/mol

25. What is the molar mass of NH3?
Step 1: determine the mass of each element
N: 14
H:1 X 3
Step 2: total the masses
14+3=17
Step 3: attach the units
17g/mol

26. Mole  Gram Conversions
When given the number of moles, MULTIPLY by the molar mass of the substance.
What is the mass of 5 moles of H2O?

27. What is the mass of 5.O moles of H2O?
Step 1: Write the given
Step 2: Multiply by molar mass
Step 3: Cancel the units
Step 4: Solve
90 grams H2O

28. Gram  Mole Conversions
When given the number of moles, DIVIDE by the molar mass of the substance.
How many moles are equivalent to 50g N?

29. How many moles are equivalent to 50g N?
Step 1: Write the given
Step 2: Divide by the molar mass
Step 3: Cancel the units
Step 4: Solve
3.57 moles N

30. Practice

31. What is the mass of … 2.22 mol Ti 1.22 X 1023 mol Ag 4.5 mol H2SO4
106 g Ti
1.22 X 1023 mol Ag
1.32 X 1025 g Ag
4.5 mol H2SO4
441 g H2SO4

32. How many moles are consumed in…
5.62 g Kr
mol Kr
55 g As
0.73 mol As
7.5 g NaCl
0.128 mol NaCl

33. End Day 2

34. Particles  Gram Conversions
Remember, particles, atoms, and molecules are all the same
To convert particles to grams…
1st: convert particles to moles
2nd: convert moles to grams

35. Review
When converting from moles to atoms, molecules, or particles, you must MULTIPLY by Avogadro’s number.
When converting atoms, particles, or molecules to moles, you must DIVIDE by Avogadro’s number.

36. What is the mass of 2.5 X 1023 atoms of H2O?
Step 1: convert atoms to moles
Step 2: convert moles to grams

37. Grams  Particles Conversions
Once again, remember particles, atoms, and molecules are all the same
To convert grams to particles…
1st: grams to moles
2nd: convert moles to particles

38. How many molecules are in 4.5 g C?
Step 1: Convert grams to moles
Step 2: Convert moles to molecules

39. Practice How many grams are in 5.0 X 1024 atoms of K?
What is the mass of 8.5 X 1023 molecules of NH2?
How many particles are in 3.75 g Ca?
How many molecules are in 96 g HBr2?

40. Practice
On your own, work pg. 347: