INTRODUCTION TO THE MOLE AND MOLAR MASS

(OWLS & MOLES LAB)

BACKGROUND

• When you buy eggs you usually ask for a _______

eggs.

• You know that one dozen of any item is ______.

Dozen

12

PAPER

• Paper is packaged in a _________.

• A ream of paper has ________ sheets.

• Why is it useful to use units like a dozen or a

ream?

Ream

500

•What determines how

many items should make

up a particular unit?

• If you were asked to design a new

unit to count pieces of candy, what

would you consider when choosing

how many items should be included in

your new counting unit?

ACTIVITY:

• WHAT YOU NEED:

• 3 packages,

• balance,

• worksheet,

• calculator,

• pencil.

PART 1

1. Follow your teacher’s instructions:

DATA TABLE 1

Name of the

Items in the

Package

Number of

items in

package

Mass of items

in the package

ANALYSIS AND INTERPRETATION

• As you know, a dozen represents 12 items.

• Since I did not have enough candy to put a dozen pieces in each bag, I decided to make a new counting unit. I called this unit an OWL.

• As you can tell, an Owl is _____ items.4

1. A OWL OF ORANGES WILL HAVE _____ ORANGES.

4

2. A OWL OF PRETZELS HAS ____ PRETZELS. 4

3. A OWL OF MOLECULES OF WATER HAS ____ MOLECULES OF WATER.

4

4. A OWL OF ATOMS OF IRON HAS _____ ATOMS OF IRON.

4

26

Fe

55.85

•Now that you understand the

meaning of an OWL, you should be

able to answer the following

questions:

1. HOW MANY HERSHEY’S KISSES ARE IN 2 OWLS? _______8

2. HOW MANY DUM DUM POPS ARE IN 400 OWLS? _______1600

3. HOW MANY STARBURSTS ARE IN 1/2 OWL? _____2

4. HOW MANY HYDROGEN ATOMS ARE IN 6OWLS? _______24

• Finding the Number of OWLS:

• If you are given the number of items you can tell the number of OWLS.

• For example, since one OWL is 4 items, 8 items make up 2 OWLS.

1. How many OWLS are 16

Hershey’s Kisses? ______4

2. How many OWLS are 100

pretzels? ____25

3. How many OWLS are 400

Starbursts? ____100

4. How many OWLS is 2

apples? ________ ½ or 0.5

OWLS VS. MOLES

• An OWL of molecules of water

would be too small to see.

• Scientists had to select a unit with a

MUCH greater value for counting

molecules because they are so small.

• The unit scientists use is called a

MOLE.

ONE MOLE OF ANYTHING HAS THIS MANY ITEMS:

602,200,000,000,000,000,000,000

•This number is written in

Scientific notation to avoid

mistakes:

6.022 x 1023

THIS IS KNOWN AS AVOGADRO’S NUMBER

•6.022 x 1023

•One MOLE of anything

has 6.022 x 1023 items.

1. HOW MANY HERSHEY’S KISSES MAKE UP 1 MOLE?

6.022 x 1023

2. HOW MANY CARAMELS MAKE UP 10 MOLES?

10 [6.022 x 1023]

60.22 x 1023

Or

6.022 x 1024

3. FIND THE NUMBER OF ATOMS OF SODIUM IN 2 MOLES.

2[6.022 x 1023 ]

12.044 x 1023

1.20 x 1024

11

Na

22.99

4. FIND THE NUMBER OF ATOMS OF CARAMELS IN 0.5 MOLES.

0.5[6.022 x 1023 ]

3.011 x 1023

5. HOW MANY MOLES ARE IN 6.022 X 1023 OF STARBURSTS?.

1 mole

6. HOW MANY MOLES ARE IN 1.204 X 1024

OF GOBSTOPPERS?.

2 moles

7. HOW MANY ATOMS OF POTASSIUM MAKE UP 1 MOLE?

1[6.022 x 1023 ]

6.022 x 1023

19

K

39.10

8. HOW MANY MOLECULES OF WATER MAKE UP 5 MOLES?

5[6.022 x 1023 ]

30.110 x 1023

3.01 x 1024

9. HOW MANY MOLES ARE IN 6.022 X 1023

OF SODIUM?

1 mole11

Na

22.99

10. HOW MANY MOLES ARE IN 1.204 X 1024 OF CARBON?

2 moles6

C

12.01

11. HOW MANY MOLES ARE 3.010 X 1024

MOLECULES OF WATER?

5 moles

PART 2

MASS

• In addition to being able to tell the number of items in an

OWL, you can now tell the mass of an OWL of Hershey’s

Kisses, Jolly Ranchers, caramels, or whatever.

DATA TABLE 1

Name of the

Items in the

Package

Number of items

in package

Mass of the

package

Candy #1

Candy #2

Candy #3

4

4

4

26.9

23.03

20.96

USE THE CLASS AVERAGE DATA IN DATA TABLE 1 TO FILL IN THE INFORMATION BELOW:

1. BASED ON YOUR MEASUREMENTS, THE MASS OF 1 OWL OF CANDY #1 IS ______ G.2. THE MEASURED MASS OF 2 OWLS OF CANDY #1 IS ______ G.3. THE MASS OF 1 OWL OF CANDY #2 IS _____ G.4. THE MASS OF 1 OWL OF CANDY #3 IS ____G5. THE MASS OF 100 OWLS OF CANDY #2 IS ____ G.6. THE MASS OF 1/2 OWL OF CANDY #3 IS ____ G.7. THE MASS OF 4 OWLS OF CANDY #2 IS ____ G.8. THE MASS OF 0.5 OWLS OF CANDY #3 IS ____ G.

MASS OF A MOLE:

As it turns out, the mass of one mole (6.022 X 1023

molecules or atoms of a substance) is THE SAME as

the atomic weight of the molecule of the element as

shown on the periodic table.

USE THE PERIODIC TABLE TO ANSWER THE FOLLOWING:

1. THE MASS OF 1 MOLE OF STRONTIUM (SR) IS ___ G.

38

Sr

87.62

87.62

2. THE MASS OF 1 MOLE OF LEAD (PB) IS ________ G.

82

Pb

207.2

207.2

3. THE MASS OF 1 MOLE OF NICKEL (NI) IS ____ G.

28

Ni

58.69

58.69

4. THE MASS OF 4 MOLES OF STRONTIUM (SR) IS _____G.

38

Sr

87.62

350.48

5. THE MASS OF 0.5 MOLES OF LEAD (PB) IS ____ G.

82

Pb

207.2

103.6

6. THE MASS OF 100 MOLES OF (NI) IS _____ G.

28

Ni

58.69

5869.00

MOLAR MASS

• Scientists also use the Periodic Table

to determine the molar mass (formula

weight) of compounds.

• The molar mass of the compound is

the sum of the molar masses of the

elements that make up the compound.

POTASSIUM CHLORIDE

• The molar mass of Potassium Chloride (KCl) is:

Potassium (K) 39.10 g/mole

Chloride (Cl) +34.45 g/mole

73.55 g/mole

POTASSIUM PERMANGANATE• The molar mass of KMnO4 is the sum of all the molar

masses times the number of atoms of each element for the

molecule (subscript).

POTASSIUM PERMANGANATE

• KMnO4

• Potassium (K) 39.10 g/mole

• Manganese (Mn) 54.94g/mole

• Oxygen (O) 4[16.00 g/mole] = 64.00g

158.04 g/mole.

1. THE MOLAR MASS OF 1 MOLE OF SODIUM CHLORIDE (NACL) IS____ 58.44 g

Na = 22.99 g

Cl = 35.45 g

2. THE MOLAR MASS OF 1 MOLE OF LEAD IODIDE (PBI2) IS _____ .461.0 g

Pb = 207.2

I = 126.9

3. THE MASS OF 100 MOLES OF NICKEL SULFIDE (NIS) IS ________ .9071.00 g

Ni = 58.65

S = 32.06

4. THE MASS OF 1 MOLE OF IS GLUCOSE (C6H12O6) IS ___________.180.16 g

5. THE MASS OF 1 MOLE OF IS SUCROSE (C12H24O12 ) _______.360.31 g

6. THE MASS OF 4 MOLES OF IS GLUCOSE (C6H12O6) IS ______ .720.62 g