1. Chemical Quantities
Ch. 7

2. Sample 1 Dimensional Analysis
Calculate the number of seconds in the month of May. (May has 31 days).
31 days  seconds?
days  hours  minutes  seconds
31 days x 24 hours x 60 minutes x 60 seconds
1 day 1 hour 1 minute
= seconds
= 2.7 x 106 seconds (2 Sig Figs)

3. Sample 2 Dimensional Analysis
2) How many kilometers is 6,228 ft? (5280 ft = 1 mile, mi = 1 km). ft  km? feet  mile  kilometer 6,228 ft x 1 mi x 1 km = 5280 ft mi = km

4. 7-1
The
Mole

5. Mole
Mole (mol) = SI unit of measure to count numbers of atoms, molecules, or formula units of substances.
Avogadro’s constant = the number of “things” (representative particles) in one mol is
6.02 x 1023
1 mol = 6.02 x 1023 representative particles (atoms/molecules/ions/formula units)
Ex: there are 6.02 x 1023 carbon atoms in a mol of carbon
Ex: there are 6.02 x 1023 eggs in a mol of eggs
The mol is good for measuring atoms (small things), NOT macroscopic things.

7. Representative Particles
Substance
Rep.
Particle
Formula
Rep. particles in 1 mol
Nitrogen
Atom N
6.02x1023
Nitrogen gas
Molecule N2
Water
H2O
Calcium ion
Ion
Ca+2
Calcium fluoride
Formula Unit (ionic)
CaF2

8. Mole Road Map (DRAW!)
ATOMS/MOLECULES

9. 1) Atoms/Molecules  Moles
6.02 x 1023
Atoms Moles
1 mol = 6.02x1023 atoms
Calculation:
__ atoms x 1 mol = _____ mol
6.02x1023 atoms
Ex: How many moles of Mg is 1.25x1023 atoms of Mg?
1.25x1023atoms Mg x 1 mol Mg =
6.02x1023atoms Mg
= 2.08x10-1mol Mg

10. Practice! How many moles is 2.80x1024 atoms of Si?
2.80x1024atoms Si x 1 mol Si =
6.02x1023atoms Si
= 4.65 mol Si

11. 2) Moles  Atoms/Molecules
6.02 x 1023
Moles Atoms
1 mol = 6.02x1023atoms
Calculation:
__ mol x 6.02x1023 atoms = _____ atoms
1 mol
Ex: 4.0 mol P = ? atoms P
4.0 mol P x 6.02x1023 atoms P
1 mol P
= 2.4x1024 atoms P

12. Practice How many molecules is 0.360mol of water?
0.360mol H2O x 6.02x1023molec H2O =
1 mol H2O
= 2.17x1023 molecules H2O

13. HONORS ONLY! 3) Moles  Molecules  Atoms
Use when going from moles  atoms for a compound!
Calculation:
___ mol x 6.02x1023molecules x __ atoms =__atoms
1 mol molecule
Ex: How many atoms are in 2.12 mol of propane (C3H8)?
2.12mol C3H8 x 6.02x1023molec C3H8 x 11 atoms =
1 mol C3H8 1 molec C3H8
=1.40x1025atoms C3H8

14. HONORS ONLY! Practice! How many atoms are there in 1.14 mol SO3?
1.14mol SO3 x 6.02x1023molec SO3 x 4 atoms =
1 mol SO molec SO3
= 2.75x1024atoms SO3
How many moles are there in 4.65x1024 molecules of NO2?
4.65x1024 molec NO2 x 1 mol NO = x1023molec NO2
= 7.72 mol NO2

15. Mole-Mass Relationships
7-2 Part I

16. Molar Mass
Molar Mass = the mass of one mol of a pure substance, expressed in grams.
Molar mass (g) = Atomic Mass (amu) on periodic table!!
Ex: What is the molar mass of carbon?
=12.0g C = 1 mol C
Ex: What is the molar mass of hydrogen?
=1.0g H = 1 mol H
Ex: What is the molar mass of cesium?
=132.9g Cs = 1 mol Cs

17. Molar Mass of a Compound
Molar mass of a compound = all of the individual atoms masses combined.
Ex: Molar mass of Ethanol C2H6O
C = 2 x 12.0g = 24.0g
H = 6 x 1.0g = 6.0g
O = 1 x 16.0g = 16.0g +
46.0g of Ethanol = 1 mol Ethanol

18. Practice! What is the molar mass of H2O2? H: 2 x 1.0g = 2.0g
O: 2 x 16.0g = 32.0g +
34.0g H2O2 = 1 mol H2O2
What is the molar mass of magnesium hydroxide?
Mg(OH)2
Mg: 1 x 24.3g = 24.3g
O: 2 x 16.0g = g
H: 2 x 1.0g = g +
58.3g Mg(OH)2 = 1 mol Mg(OH)2

19. 4) Moles  Mass Molar Mass Moles Mass 1 mol = molar mass (g)
Calculation:
___ mol x molar mass(g) = ___ grams
1 mol
Ex: How many grams are in 9.45 moles of dinitrogen trioxide?
Molar Mass N2O3 = 2x14.0g + 3x16.0g = 76.0g
9.45mol N2O3 x 76.0g N2O3 = ? g
1 mol N2O3
= 718g N2O3

20. 5) Mass  Moles Molar Mass Mass Moles 1 mol = Molar Mass (g)
Calculation:
___ mass (g) x 1 mol = ___ mol
molar mass(g)
Piece of iron (III) oxide is 16.8g. How many moles are in the sample?
Molar Mass Fe2O3: 2x55.8g + 3x16.0g = 159.6g
16.8g Fe2O3 x 1 mol Fe2O3 = ? mol
159.6g Fe2O3
= mol Fe2O3

21. Try It! Determine the mass of the following:
3.52 mol of Si
3.52mol Si x 28.1g Si = ? g
1 mol Si
=98.9g Si
Determine the moles of the following:
1.25g of aspirin, C9H8O
Molar mass C9H8O = 9x x1.0g + 1x16.0g = ? g
= 132.0g
1.25g C9H8O x 1 mol C9H8O =
132.0g C9H8O
= mol C9H8O

22. 6) Mass  Moles  Atoms/ Molecules
Molar
Mass
6.02 x 1023
Mass Moles Atoms/Molecules
1 mol = Molar Mass (g);
1 mol = 6.02x1023atoms
Calculation:
Mass(g) x 1 mol x 6.02 x 1023 atoms = atoms molar mass(g) mol
16.8g of Fe into atoms of Fe:
16.8g Fe x 1 mol Fe x x 1023 atoms Fe
55.8g Fe mol Fe
= 1.81 x 1023 atoms Fe

23. Try it! Determine the # of atoms in the following:
98.3g of Hg: Mass  Mol  Atom
98.3g x 1 mol x x1023 atoms = g mol
= 2.95 x 1023 atoms Hg
45.6g of Au:
45.6g x 1 mol x x1023 atoms = g mol
= 1.39 x 1023 atoms Au

24. Determine the # of grams in the following:
Atoms  Mol  Mass
9.33 x 1023atoms Li:
9.33 x 1023atoms Li x mol x g = x1023atoms 1 mol
= 10.7g Li
4.757x1023atoms W:
4.757x1023atoms x mol x g = x1023 atoms mol
= 145.2g W

25. Mole-Volume Relationships
7-2 Part II

26. Molar Volume
Standard Temperature and Pressure (STP) = O°C at 1 atmosphere (atm) or 101.3kPa
Molar Volume of a gas is the volume that a mole of gas occupies at STP
At STP, 1 mol = 22.4L

27. 7) Moles  Volume Molar Volume Moles Volume (Liters) 1 mol = 22.4 L
Calculation:
___ mol x 22.4L = ___ L
1 mol
What is the volume (L) of 0.60 mol SO2 gas at STP?
0.60mol SO2 x 22.4 L SO2 = ? L mol SO2
= 13 L SO2

28. 8) Volume  Moles Volume (Liters) Moles 1 mol = 22.4 L Calculation:
Molar Volume
Volume (Liters) Moles
1 mol = 22.4 L
Calculation:
___ L x 1 mol = ___ mol
22.4 L
How many moles are in 7.2 L of H2O2 at STP?
7.2 L H2O2 x 1 mol H2O2 = ?
22.4 L H2O2
= 0.32mol H2O2

29. Practice! What is the volume of 3.20x10-3mol CO2 at STP?
3.20x10-3 mol CO2 x 22.4 L CO2 = ?
1 mol CO2
= or 7.17x10-2 L CO2
How many moles are in 5.2 L of H2O at STP?
5.2 L H2O x 1 mol H2O = ? L H2O
= 0.23 mol H2O

30. Mole Road Map Mass Atom Mole Volume Molar Mass 1 mol = Avogadro’s #
Molar mass (g)
Avogadro’s #
1 mol = 6.02x1023 atoms
Molar
Volume
1 mol =
22.4L
Volume

32. 1) 1 mol = _____ L
6.02x1023
Molar mass
22.4
1.0

33. 2) 1 mol = ____ atoms
6.02x1023
Molar mass
22.4
1.0

34. 3) What is the molar mass of C6H12O6?
24.0g
64.0g
180.0g
348.0g

35. 4) How many atoms are in 16g N? Choose correct set-up.
16g x 14.0g x x1023 atoms =
1 mol mol
16g x 1 mol x mol =
14.0g x1023 atoms
16g x 14.0g x mol =
1 mol x1023 atoms
16g x 1 mol x x1023 atoms =
14.0g mol

36. Answers C A D