1. Ch10.1 – The Mole
1 mole = 6.02 x 1023 particles
This is called Avogadro’s Number
*Think of it as a chemist’s dozen
(A dozen donuts or a mole of donuts?)
Can be used for atoms, ions, molecules, donuts, oranges,
grains of sand, chevys, etc.
Why that number?
-Since 1 amu = 1.66 x 10-24g:
= 1 x

2. The Mole
Can use as a unit for counting numbers
Atoms are too small to count individually and there are too many, so we need a way to bundle a bunch, like having a dozen oranges = 12 oranges
1 mole = 6.02 x 1023 particles
This is hard to understand, so let’s relate it.
Did You Know???
A grain of rice has an average mass of 1.75 x 10-5kg. What is the mass of one mole, 6.02 x 1023, grains of rice? x 1019 kilograms This is hard to understand, so let’s change this mass to the mass of cars. This would require a million cars per person to equal this mass!!
You can count the number of oranges in 6 dozen in a few minutes. Six moles of oranges would have a mass as large as the entire Earth!
Avogadro’s number (1 mole) is so large, if you could count 100 particles every minute and counted 12 hrs every day, and had every person on Earth also counting, it would take more than 4 million years to count a mole of anything!
To obtain Avogadro’s number in grains of sand, would cover an area
of the United States to a depth of 200m! (2 football fields deep!)

3. Conversions: or
6.02 x 1023 particles
1 mol
Ex 1) How many moles of Mg are 3.01 x 1022 atoms?
Ex 2) How many molecules are 4.00 mol of glucose, C6H12O6?
HW#2) How many atoms are 0.360mol of Silver?

4. Gram Formula Mass
Ex3) He weighs or
C weighs or
The mole # was chosen so that the # on the Periodic Table
can be read in grams.
*Round masses on the periodic table to nearest 1/10*
Ex4) H F Cl

5. Ex4) Find the molecular mass of:
H2O
NaCl
Mg3 (PO4)2
Ch10 HW#1 1 – 7

6. Ch10 HW#1 1 – 7
1) How many moles in 2.80 x 1024 atoms of silicon?
2) How many atoms are 0.360mol of Silver? (in class)
3) How many oxygen atoms in each: A) NH4NO3 B) C9H8O4 C) O3 D) C3H5(NO3)3

7. 4) How many molecules in 2.14 mol CO?
5) How many moles in 4.65 x 1024 molecules of NO2?

8. 4) How many molecules in 2.14 mol CO?
5) How many moles in 4.65 x 1024 molecules of NO2?
6.02 x 1023 molecules
2.14 mol CO
1 mol CO

9. 4) How many molecules in 2.14 mol CO?
5) How many moles in 4.65 x 1024 molecules of NO2?
6.02 x 1023 molecules
2.14 mol CO
1 mol CO
4.63 x 1024 molecules
1 moles
6.02 x 1023 molecules

10. 6) Gram molecular mass
A. C2H B. PCl3
C. C3H7OH D. N2O5

11. 6) Gram molecular mass
A. C2H B. PCl3
C. C3H7OH D. N2O5 =
= 24.0
= 106.5
= 6.0
137.5 g/mol
30.0 g/mol

12. 7) Gram Formula Mass
A. Sr(CN)2 B. NaHCO3
C. Al2(SO3)3

13. Ch10.2 – Mole/Mass Conversions
Ex 1) How many grams are in 7.20 mol of dinitrogen trioxide?
Ex 2) How many grams are in 3.41 mol of calcium oxide?
Ex 3) Find the number of moles in 92.81g of Iron (III) Oxide?

14. Ch10.2 – Mole/Mass Conversions
Ex 1) How many grams are in 7.20 mol of dinitrogen trioxide?
Ex 2) How many grams are in 3.41 mol of calcium oxide?
7.20 mol N2O3
76.0 grams N2O3
= 547 grams N2O3
1 mol N2O3
= 28.0
= 48.0
76.0 g/mol
= 191 grams CaO
Ex 3) Find the number of moles in 92.81g of Iron (III) Oxide?
= .581 Moles

15. HW#8) Find the mass of each:
0.720 mol Be
b) mol N2
(finish c, d)
HW#9) Find # of moles in each:
b) g Li2HPO4
(finish #9)
Ch10 HW#2 8,9

16. Ch10HW#2 8 – 9
8c) Convert to mass:
10.0 mol Cr
d) mol K

17. 8c) Convert to mass:
10.0 mol Cr g Cr
1 mol Cr = 520g Cr
d) mol K g K
1 mol K = 130 g K

18. 8c) Convert to mass:
10.0 mol Cr g Cr
1 mol Cr = 520g Cr
d) mol K g K
1 mol K = 130 g K
9) Find moles
a) 5.00g H2
c) 72.0g Ar
d) 3.70x10 -1 g

19. Ch10.3 – Using the Mole
Ex) What is the mass of 3.01x1023 atoms of Carbon?
Ex) What is the mass of 12.04x1023 molecules of oxygen?
Ex) How many molecules are there in 63.8g of ethanol, CH3OH?
Ch10 HW #3 (10-12)

20. Ch10.3 – Using the Mole
Ex) What is the mass of 3.01x1023 atoms of Carbon?
3.01x1023 atoms C 1 mol C g C
6.02x1023 atoms C 1 mol C = 6.00g C
Ex) What is the mass of 12.04x1023 molecules of oxygen?
12.04x1023 molecules O mol O g O2
6.02x1023 molec. O2 1 mol O2 = 64.0g O2
Ex) How many molecules are there in 63.8g of ethanol, CH3OH?
63.8g CH3OH 1 mol CH3OH 6.02 x 1023 molecules CH3OH
32.0g CH3OH mol CH3OH
= 1.20 x 1024 molecules CH3OH
Ch10 HW #3 (10-12)

21. Lab10.1 – Molar Mass
- due tomorrow
- Ch10 HW#3 due at beginning of period

22. Ch10 HW #3 10 – 12
10) What is the mass of 2.11 x 1024 molecules of sulfur dioxide?
2.11 x 1024 molecules SO2
= 32.1
2 16 =
64.1 g/mol

23. 10) What is the mass of 2.11 x 1024 molecules of sulfur dioxide?
2.11 x 1024 molecules SO2
1 moles SO2
64.1g SO2
6.02 x 1023
molecules SO2
1 moles SO2
= 32.1
2 16 =
64.1 g/mol

24. 11) What is the mass of 1.0 x 1022 molecules of iodine?
1.0 x 1022 molecules I2
= g/mol

25. 11) What is the mass of 1.0 x 1022 molecules of iodine?
1.0 x 1022 molecules I2
1 moles I2
253.8g I2
6.02 x 1023
molecules I2
1 moles I2
= g/mol

26. 12) How many molecules is 126.7g of sucrose?
126.7g C6H12O6
= 72.0
= 12.0
= 96.0
180.0 g/mol

27. 12) How many molecules is 126.7g of sucrose?
6.02 x 1023
molecules C6H12O6
126.7g C6H12O6
1 mol C6H12O6
180.0g C6H12O6
1 mol C6H12O6
= 72.0
= 12.0
= 96.0
180.0 g/mol

28. Ch10.4 – Volume of a Mole of Gas
Volumes of gases can change a lot, if temp or pressure change.
Standard temperature and pressure: (STP)
Temp: 0°C (273K)
Pressure: kPa (kiloPascals) or 1 atmosphere
At STP, 1 mole of any gas occupies a volume of 22.4 Liters.
22.4 L
1 mol
1 mol
22.4 L or

29. Ch10.4 – Volume of a Mole of Gas
Volumes of gases can change a lot, if temp or pressure change.
Standard temperature and pressure: (STP)
Temp: 0°C (273K)
Pressure: kPa (kiloPascals) or 1 atmosphere
At STP, 1 mole of any gas occupies a volume of 22.4 Liters.
Ex 1) What is the volume of mol of SO2 gas at STP?
22.4 L
1 mol
1 mol
22.4 L or

30. Ch10.4 – Volume of a Mole of Gas
Volumes of gases can change a lot, if temp or pressure change.
Standard temperature and pressure: (STP)
Temp: 0°C (273K)
Pressure: kPa (kiloPascals) or 1 atmosphere
At STP, 1 mole of any gas occupies a volume of 22.4 Liters.
Ex 1) What is the volume of mol of SO2 gas at STP?
22.4 L
1 mol
1 mol
22.4 L or
0.600 mol SO2
22.4 L SO2
= 13.4 L SO2
1 mol SO2

31. Ex 2) Determine the # of moles in 33.6 L of He gas at STP:
Ex 3) The density of a gaseous compound of C and O is g/L
at STP. Determine the gram formula mass. Is it CO or CO2?
CO: = 12.0
= 16.0
20.0 g/mol
CO2: = 12.0
= 32.0
44.0 g/mol

32. Ex 2) Determine the # of moles in 33.6 L of He gas at STP:
Ex 3) The density of a gaseous compound of C and O is g/L
at STP. Determine the gram formula mass. Is it CO or CO2?
1.964g
1 L
1 mol He
= 1.50 mol He
22.4 L He
CO: = 12.0
= 16.0
20.0 g/mol
CO2: = 12.0
= 32.0
44.0 g/mol

33. Ex 2) Determine the # of moles in 33.6 L of He gas at STP:
Ex 3) The density of a gaseous compound of C and O is g/L
at STP. Determine the gram formula mass. Is it CO or CO2?
1.964g
1 L
1 mol He
= 1.50 mol He
22.4 L He
1.964g
1 L
22.4 L
= 44.0 g/mol
1 mol
CO: = 12.0
= 16.0
20.0 g/mol
CO2: = 12.0
= 32.0
44.0 g/mol

34. Ex4) 10.4g of dry ice, CO2 , is allowed to sublime into a gas.
If the gas is brought to STP, what volume does it occupy?
Ex5) 1.13x1022 molecules of hydrogen gas occupy what volume
at STP?

35. Ex4) 10.4g of dry ice, CO2 , is allowed to sublime into a gas.
If the gas is brought to STP, what volume does it occupy?
= 5.29L CO2
10.4g CO2
1 mol CO2
22.4L CO2
44.0g CO2
Ex5) 1.13x1022 molecules of hydrogen gas occupy what volume
at STP?

36. Ex4) 10.4g of dry ice, CO2 , is allowed to sublime into a gas.
If the gas is brought to STP, what volume does it occupy?
= 5.29L CO2
10.4g CO2
1 mol CO2
22.4L CO2
44.0g CO2
Ex5) 1.13x1022 molecules of hydrogen gas occupy what volume
at STP?
= .420L H2
1.13x1022 molecules H2
1 mol H2
22.4L H2
6.02x1023 molecules H2
Ch10 HW#

37. CO2 O2 H2 Ch10 HW#4 13-18 ( XC for correct #16 )
13) 3 balloons each contain the same # of molecules of 3 different STP.
Same mass? Same volume?
CO2 O2 H2

38. 14) STP
a) 3.20x10-3 mol CO L CO2
1 mol CO2 =
b) mol CH L CH4
1 mol CH4 =
c) 3.70 mol N L N2
1 mol N2 =
15) At STP, how many moles?
a) 67.2L SO mol SO2
22.4 L SO2 =
b) 0.880L He 1 mol He
22.4 L He =
c) 1.00x103L C2H6 1 mol C2H6
22.4 L C2H6 =

39. 16) AT STP what volume does 12.2g fluorine gas occupy?
12.2 g F2 1 mol F L F2
38.0 g F mol F2 =
17) 13.0 x 1024 molecules of Argon occupy what volume at STP?
13.0 x 1024
molecules Ar 1 mol Ar L Ar
6.02 x mol Ar =
molecules Ar

40. 18) The densities of 3 gases:
A: 1.25 g/L B: 2.86 g/L
C:0.714 g/L
Calculate the gFm of each (g/mol)
ID as NH3, SO2, Cl2, N2, or CH4
1.25 g L
1 L mol =
B) g L
C) g L
NH3: 14.0 = 14.0
= 3.0
17.0 g/mol
SO2: = 32.1
= 32.0
64.1 g/mol
Cl2: = g/mol
N2: = g/mol
CH4: = 12.0
= 4.0
16.0 g/mol

41. Ch10.5 – More Conversions
Ex1) One copper cylinder from the last lab had a mass of 57.68g.
How many copper atoms is that?
Ex2) Dinitrogen monoxide is stored in a 2.00 L cylinder at STP.
What mass is this?

42. Ch10.5 – More Conversions
Ex1) One copper cylinder from the last lab had a mass of 57.68g.
How many copper atoms is that?
57.68g Cu 1 moles Cu x1023 atoms
63.5g Cu moles Cu = 5.47x1023 atoms Cu
Ex2) Dinitrogen monoxide is stored in a 2.00 L cylinder at STP.
What mass is this?
2.00 L N2O 1 moles N2O g N2O
22.4 L N2O moles N2O = 3.93 g N2O

43. Ex3) Hydrogen sulfide is a dangerous gas released in volcanoes.
If a scientist collects 10.0 mL sample at STP,
how many gas particles are present?

44. Ex3) Hydrogen sulfide is a dangerous gas released in volcanoes.
If a scientist collects 10.0 mL sample at STP,
how many gas particles are present?
.0100L H2S 1 mole H2S 6.02x1023 particles H2S
22.4 L H2S moles H2S = 2.69x1020 particles
Ch10 HW#

45. Ch10 HW#5 19 – 22
19. One sodium chloride salt crystal is carefully separated from
the salt shaker, and massed at 0.01 grams.
How many sodium ions are in the crystal?
20. A CO2 cartridge for a BB gun has 12 grams of CO2 stored
at high pressure. If the cartridge is punctured and the gas collected,
what volume would the CO2 occupy, when allowed to reach standard
conditions?

46. 19. One sodium chloride salt crystal is carefully separated from
the salt shaker, and massed at 0.01 grams.
How many sodium ions are in the crystal?
0.01 g NaCl 1 mol NaCl 1 mol Na x1023 ions
58.5 g NaCl 1 mol NaCl mol Na+
20. A CO2 cartridge for a BB gun has 12 grams of CO2 stored
at high pressure. If the cartridge is punctured and the gas collected,
what volume would the CO2 occupy, when allowed to reach standard
conditions?
12 g CO mol CO L
44.0 g CO2 1 mol CO2

47. 21. Find the mass in grams of 4.52 x 1023 molecules C20H42
4.52x1023 molecules C20H mol C20H g C20H42
6.02x1023 molecules C20H42 1 mol C20H42
22. Find the number of molecules in 11.0 g CH4
11.0 g CH mol CH x1023 molecules CH4
16.0 g CH4 1 mol CH4

48. 21. Find the mass in grams of 4.52 x 1023 molecules C20H42
4.52x1023 molecules C20H mol C20H g C20H42
6.02x1023 molecules C20H42 1 mol C20H42
22. Find the number of molecules in 11.0 g CH4
11.0 g CH mol CH x1023 molecules CH4
16.0 g CH4 1 mol CH4

49. Ch10.6 Percent Composition
Ex1) Calculate the percent composition (by mass) of glucose, C6H12O6.

50. Ch10.6 Percent Composition
Ex1) Calculate the percent composition (by mass) of glucose, C6H12O6.
= 72.0 g
= 12.0 g
= 96.0g
180.0g
%C: %H: %O:
= 40%
= 7%
= 53%

51. Ex2) Calculate the empirical formula of a compound that is
experimentally found to be 27.59% Carbon,
1.15% Hydrogen, 16.09% Nitrogen, and 55.17% Oxygen
Ch10 HW#6 23 – 25

52. Ch10 HW#6 23 – 25
23. Calculate the percent composition of hydrogen cyanide, HCN.
= g
= 12.0 g
= 14.0g
27.0g
%H: %C: %N:

53. 24. Which of the following molecular formulas
are also empirical formulas?
a. ribose, C5H10O5, sugar molecule in RNA
b. ethyl brutanoate, C6H12O2,
a compound with the odor of a pineapple
c. chlorophyll, C55H72MgN4O5, part of photosynthesis
d. DEET, C12H17ON, an insect repellent
e. Oxalic acid, H2C2O4, found in spinach and tea

54. 25. Calculate the empirical formula of each compound
with the following percent composition.
a % O, 5.9% H
94.1 g O 1 mol O
16.0 g O
5.9 g H 1 mol H
1.0 g H
b % C, 20.1% H
c % Hg, 10.8% S, 21.6% O
d. 17.6% Na, 39.7% Cr, 42.7 O
= 5.9 mol O
= 5.9 mol H

55. 25. Calculate the empirical formula of each compound
with the following percent composition.
c % Hg, 10.8% S, 21.6% O
67.6g Hg 1 mol Hg
200.6 g Hg
10.8g S 1 mol S
32.1 g S
21.6g O 1 mol O
16.0 g O
d. 17.6% Na, 39.7% Cr, 42.7 O
17.6g Na 1 mol Na
23.0 g Na
39.7g Cr 1 mol Cr
52.0 g Cr
42.7g O 1 mol O
= 0.34 mol Hg
= 0.34 mol S
= 1.35 mol O
= 0.77 mol Na
= 0.76 mol Cr
= 2.67 mol O

56. Ch10.7 Empirical and Molecular Formulas
Ex1) What is the empirical formula of a compound that is 92.3% carbon
and 7.7% hydrogen? If the actual molecule has a molar mass of 26.0 g/mol,
what is the molecular formula?

57. Ch10.7 Empirical and Molecular Formulas
Ex1) What is the empirical formula of a compound that is 92.3% carbon
and 7.7% hydrogen? If the actual molecule has a molar mass of 26.0 g/mol,
what is the molecular formula?
92.3 g C mol C
12.0 g C
= 7.7 mol C CH
7.7 g H mol H
1.0 g H
= 7.7 mol H
CH = 13.0 g/mol
26.0 / = 2  C2H2

58. Ex2) What is the empirical formula of a compound that is 40% carbon,
6.7% hydrogen, and 53.3% oxygen?
If the molecule has a molar mass of g/mol, what is the molecular formula?
Ch10 HW#7 26 – 28

59. = 3.3 mol C CH2O = 6.7 mol H CH2O = 30.0 g/mol = 3.3 mol O
Ex2) What is the empirical formula of a compound that is 40% carbon,
6.7% hydrogen, and 53.3% oxygen?
If the molecule has a molar mass of g/mol, what is the molecular formula?
Ch10 HW#7 26 – 28
40 g C mol C
12.0 g C
= 3.3 mol C
6.7 g H mol H
1.0 g H
CH2O
= 6.7 mol H
CH2O = 30.0 g/mol
53.3 g O mol O
16.0 g O
= 3.3 mol O
180.0 / = 6  C6H12O6

60. Ch10 HW#7 26 – 28
26. The empirical formula for a substance was found to be CH4N. It has a molar mass
of 60 g/mol. What is the molecular formula?
27. What is the empirical formula of a compound that is 39.7% carbon,
1.7% hydrogen, and 58.6% chlorine?
If the molecule has a molar mass of g/mol, what is the molecular formula?

61. Ch10 HW#7 26 – 28
26. The empirical formula for a substance was found to be CH4N. It has a molar mass
of 60 g/mol. What is the molecular formula?
= 12.0 g
= g
= 14.0g
30.0g
27. What is the empirical formula of a compound that is 39.7% carbon,
1.7% hydrogen, and 58.6% chlorine?
If the molecule has a molar mass of g/mol, what is the molecular formula?

62. = 3.3 mol C = 1.7 mol H = 1.7 mol Cl Ch10 HW#7 26 – 28
26. The empirical formula for a substance was found to be CH4N. It has a molar mass
of 60 g/mol. What is the molecular formula?
= 12.0 g
= g
= 14.0g
30.0g
27. What is the empirical formula of a compound that is 39.7% carbon,
1.7% hydrogen, and 58.6% chlorine?
If the molecule has a molar mass of g/mol, what is the molecular formula?
39.7 g C mol C
12.0 g C
= 3.3 mol C
1.7 g H mol H
1.0 g H
= 1.7 mol H
58.6 g Cl mol Cl
35.5 g Cl
= 1.7 mol Cl

63. 28. Methyl butanoate smells like apples. It is 58. 8% carbon, 9
28. Methyl butanoate smells like apples. It is 58.8% carbon, 9.8% hydrogen,
and 31.4% oxygen. Its gram molecular mass of g/mol.
What is the molecular formula?

64. 28. Methyl butanoate smells like apples. It is 58. 8% carbon, 9
28. Methyl butanoate smells like apples. It is 58.8% carbon, 9.8% hydrogen,
and 31.4% oxygen. Its gram molecular mass of g/mol.
What is the molecular formula?
58.8 g C mol C
12.0 g C
= 4.9 mol C / 2 = 2.5  5
9.8 g H mol H
1.0 g H
= 9.8 mol H / 2 = 5  10
31.4 g O mol O
16.0 g O
= 1.9 mol O / 2 = 1  2

65. Ch10 Review
How many moles in 1.50x1023 molecules NH3?
2) Calculate the gram formula mass of H3PO4. 3 1 4
3) How many moles in 15.5 g SiO2?

66. Ch10 Review
How many moles in 1.50x1023 molecules NH3?
1.50x1023 molecules NH3 1 mol NH3
6.02x1023 molecules NH3 =.249 moles NH3
2) Calculate the gram formula mass of H3PO4. =
= = 98.0 g/mol
= 64.0
3) How many moles in 15.5 g SiO2?

67. 3) How many moles in 15.5 g SiO2?
4) Find the mass of 1.50 moles C5H12

68. 3) How many moles in 15.5 g SiO2?
15.5 g SiO mol SiO2
60.1 g SiO2 = .257 mol SiO2
4) Find the mass of 1.50 moles C5H12
1.50 moles C5H g C5H12
1 mol C5H12 = 108 g C5H12

69. 5) Calculate the volume of 7.6 mole Ar at STP.
6) Find the volume of 835 g SO3 at STP.

70. 5) Calculate the volume of 7.6 mole Ar at STP.
7.6 mol Ar L Ar
1 mol Ar = 170 L Ar
6) Find the volume of 835 g SO3 at STP.
835g SO mol SO L SO3
80.1 g SO mol SO3 = 234 L SO3

71. 7. Calculate the % composition of H and S in H2S.
8. Find the empirical formula of a compound that is
65.2% Sc and 34.8% O.

72. 9. Determine the molecular formula for a compound that is
94.1% O and 5.9% H, with a gfm of 34 g/mol.
10. How many molecules in 97.3 g of potassium oxide?

73. 11. What is the volume of gas 28.0 g of a neon?
12. A lab group finds that when magnesium combines with
oxygen to form a compound, the percent composition is
60.3% Mg and 39.7% O. What is the empirical formula
of this compound?

74. Ch10 Extra Practice
How many atoms are in 1.23 moles of calcium?
How many grams are in 1.23 moles of calcium?
How many moles of carbon are in 5.5 g sample of carbon?

75. 4. How many moles of aluminum are there in 2.3x1024 atoms?
5. How many liters are in 2.50 moles of hydrogen molecules, H2?

76. 6. How many moles are in 3.04 liters of chlorine gas?
7. How many particles are in 55.6 g of calcium oxide?
8. How many liters of gas are produced when 10.3 g of dry ice,
solid carbon dioxide, sublimes?