1 of 50

Daily Question

What would be the charge of an iodide ion? Which is larger I? or I^1-?

.

10.1 The Mole: A Measure-ment of Matter

1

>

2 of 50

.

Chapter 10

Chemical Quantities

10.1 The Mole: A Measurement of Matter

10.1 The Mole: A Measure-ment of Matter

2

>

3 of 50

I can…

Perform dimensional analysis to convert between units

Recall Avogadro’s number

Apply Avogadro’s number to determine the number of representative particles in a substance

Calculate representative particles 🡪 moles

Calculate moles 🡪 representative particles

Determine molar mass of a substance

.

10.1 The Mole: A Measure-ment of Matter

3

>

4 of 50

Measuring Matter

Chemistry is a quantitative science.

.

you perform calculations that relate quantities of the reactants in a chemical reaction to quantities of the products.

10.1 The Mole: A Measure-ment of Matter

4

>

5 of 50

Measuring Matter

Each of these different ways to measure apples can be equated to a dozen apples.

By count: 1 dozen apples = 12 apples
By mass: 1 dozen apples = 2.0 kg apples
By volume: 1 dozen apples = 0.20 bushel apples

These are approximations for average-sized apples.

.

10.1 The Mole: A Measure-ment of Matter

5

>

6 of 50

What is the mass of 90 average-sized apples if 1 dozen of the apples has a mass of 2.0 kg?

.

Sample Problem 10.1

Finding Mass from a Count

10.1 The Mole: A Measure-ment of Matter

6

>

7 of 50

.

Use dimensional analysis to convert the number of apples to the mass of 90 apples.

KNOWNS

number of apples = 90 apples

Conversion factors�12 apples = 1 dozen apples�1 dozen apples = 2.0 kg apples

UNKNOWN�mass of 90 apples = ? kg

Sample Problem 10.1

Analyze List the knowns and the unknown.

1

10.1 The Mole: A Measure-ment of Matter

7

>

8 of 50

.

Multiply the known by conversion factors.

The conversion factor used should cancel the previous unit

The unit “apples” cancels the previous unit

Sample Problem 10.1

Calculate Solve for the unknown.

2

90 apples ×

×

= 15 kg apples

12 apples

1 dozen apples

2.0 kg apples

The unit “dozen apples” cancels the previous unit

10.1 The Mole: A Measure-ment of Matter

8

>

9 of 50

If 0.20 bushel is 1 dozen apples and a dozen apples has a mass of 2.0 kg, what is the mass of 0.56 bushel apples?

KNOWNS

number of apples = 0.56 bushel apples Conversion factors�12 apples = 1 dozen apples�1 dozen apples = 2.0 kg apples

UNKNOWN�mass of 0.56 bushel apples = ? kg

.

10.1 The Mole: A Measure-ment of Matter

9

>

10 of 50

COPY THIS

Assume 2.0 kg of apples is 1 dozen and that each apple has 8 seeds. How many apple seeds are in 14 kg of apples?

Known – 14 kg apples

Conversion factors:

2.0 kg apples = 1 dozen

1 apple = 8 seeds

Unknown: seeds?

.

10.1 The Mole: A Measure-ment of Matter

10

>

11 of 50

What Is a Mole?

These is an extremely large number of them in a small sample of a substance so counting these particles is not practical.

.

Matter is composed of atoms, molecules, and ions.

10.1 The Mole: A Measure-ment of Matter

11

>

12 of 50

What Is a Mole?

Think about counting eggs.

.

It’s easier when the eggs are grouped into dozens.
A dozen is a

specified number

(12) of things.

10.1 The Mole: A Measure-ment of Matter

12

>

13 of 50

What Is a Mole?

Chemists also use a unit that is a specified number of particles, most often atoms or molecules.

The unit is called the mole.
A mole (mol) of a substance is 6.022 × 10²³ representative particles of that substance
The number of representative particles in a mole and is called Avogadro’s number, 6.022 × 10²³

.

Counting with Moles

TED Ed TV

10.1 The Mole: A Measure-ment of Matter

13

>

14 of 50

If you had a mole of doughnuts, they would cover the entire Earth in a doughnut-layer five miles deep.

.

10.1 The Mole: A Measure-ment of Matter

14

>

15 of 50

If you had a mole of basketballs, you could create a new planet the size of the Earth!

.

10.1 The Mole: A Measure-ment of Matter

15

>

16 of 50

If you received a mole of pennies on the day you were born, and spent a million dollars a second until you died at 100, you’d still have over 99.99% of your money in the bank!

.

10.1 The Mole: A Measure-ment of Matter

16

>

17 of 50

The term representative particle refers to atoms, molecules, or formula units.

The representative particle of most elements is the atom.

.

Counting with Moles

10.1 The Mole: A Measure-ment of Matter

17

>

18 of 50

What Is a Mole?

However, seven elements exist normally as diatomic molecules: H₂, N₂, O₂, F₂, Cl₂, Br₂, and I₂.

I Have NO Bright or Clever Friends – you must memorize the diatomic elements

The representative particle of these elements is the molecule.
For ionic compounds, such as calcium chloride, the representative particle is the formula unit, CaCl₂.

.

Counting with Moles

10.1 The Mole: A Measure-ment of Matter

18

>

19 of 50

What Is a Mole?

A mole of any substance contains Avogadro’s number of representative particles, or 6.022 × 10²³ atoms, ions, molecules or formula units

.

Counting with Moles

10.1 The Mole: A Measure-ment of Matter

19

>

20 of 50

COPY THIS

Write the correct representative particle (atom , molecule or formula unit) for each of the following.

H₂O

KI

O₂

Ag

.

10.1 The Mole: A Measure-ment of Matter

20

>

21 of 50

Daily Question

What is a mole of substance?

.

10.1 The Mole: A Measure-ment of Matter

21

>

22 of 50

Magnesium is a light metal used in the manufacture of aircraft, automobile wheels, and tools. How many moles of magnesium is 1.25 × 10²³ atoms of magnesium?

.

Sample Problem 10.2

Converting Number of Atoms to Moles

10.1 The Mole: A Measure-ment of Matter

22

>

23 of 50

.

KNOWN

number of atoms = 1.25 × 10²³ atoms Mg

Conversion factor

1 mol Mg = 6.022 × 10²³ atoms Mg

UNKNOWN�moles = ? mol Mg

Sample Problem 10.2

Analyze List the known and the unknown.

1

10.1 The Mole: A Measure-ment of Matter

23

>

24 of 50

.

Multiply the number of atoms of Mg by the conversion factor.

6.022 × 10²³ atoms Mg

1 mol Mg

1.25 × 10²³ atoms Mg ×

= 0.208 mol Mg

Calculate Solve for the unknown.

2

Sample Problem 10.2

Why does this answer have three significant figures?

10.1 The Mole: A Measure-ment of Matter

24

>

25 of 50

How many moles is 2.8 x 10²⁴ atoms of silicon?

.

10.1 The Mole: A Measure-ment of Matter

25

>

26 of 50

How many moles is 2.17 x 10²³ representative particles of bromine?

.

10.1 The Mole: A Measure-ment of Matter

26

>

27 of 50

What Is a Mole?

A mole of carbon dioxide contains 6.022 × 10²³ (Avogadro’s number) of CO₂ molecules.
1 mole of CO₂contains three atoms, so it contains three times 6.022 × 10²³ atoms or 1.806 × 10²⁴atoms

.

Converting Between Number of Particles and Moles

10.1 The Mole: A Measure-ment of Matter

27

>

28 of 50

Propane is a gas used for cooking and heating. How many atoms are in 2.12 mol of propane (C₃H₈)?

.

Sample Problem 10.3

Converting Moles to Number of Atoms

10.1 The Mole: A Measure-ment of Matter

28

>

29 of 50

.

KNOWN�number of moles = 2.12 mol C₃H₈

Conversion factors�1 mol C₃H₈ = 6.022 × 10²³ molecules C₃H₈�1 molecule C₃H₈ = 11 atoms (3 carbon and 8 hydrogen atoms)

UNKNOWN�number of atoms = ? atoms

The desired conversion is:

moles → molecules → atoms.

Sample Problem 10.3

Analyze List the knowns and the unknown.

1

10.1 The Mole: A Measure-ment of Matter

29

>

30 of 50

.

Multiply the moles of C₃H₈ by the conversion factors.

= 1.40 × 10²⁵ atoms

Sample Problem 10.3

Calculate Solve for the unknown.

2

1 molecule C₃H₈

2.12 mol C₃H₈ ×

6.022 × 10²³ molecules C₃H₈

1 mol C₃H₈

×

11 atoms

Why does the answer have three significant figures?

10.1 The Mole: A Measure-ment of Matter

30

>

31 of 50

How is a mole similar to a dozen?

.

10.1 The Mole: A Measure-ment of Matter

31

>

32 of 50

How many atoms are in 1.14 mol of sulfur trioxide (SO₃)?

.

10.1 The Mole: A Measure-ment of Matter

32

>

33 of 50

How many carbon atoms are in 2.12 mol of propane?

How many hydrogen atoms are in 2.12 mole of propane?

.

10.1 The Mole: A Measure-ment of Matter

33

>

34 of 50

Daily Question

How many molecules of H₂O are in 1 mole of H₂O?

.

10.1 The Mole: A Measure-ment of Matter

34

>

35 of 50

Learning Targets: I can…

Determine molar mass of an element or compound
Calculate moles to grams
Calculate grams to moles

.

10.1 The Mole: A Measure-ment of Matter

35

>

36 of 50

Molar Mass

The atomic mass of an element expressed in grams is the mass of a mole of the element.

The mass of 1 mole of an element is its molar mass.

For carbon, the molar mass is 12.0 g.

For atomic hydrogen, the molar mass is 1.0 g.

.

The Mass of a Mole of an Element

10.1 The Mole: A Measure-ment of Matter

36

>

37 of 50

.

Why are the atomic masses on the periodic table not whole numbers?

What is the atomic mass of an element expressed in grams?

10.1 The Mole: A Measure-ment of Matter

37

>

38 of 50

Molar Mass

This figure shows one mole of carbon, sulfur, and iron.

.

The Mass of a Mole of an Element

1 mol of carbon atoms = 12.0 g

1 mol of sulfur atoms = 32.1 g

1 mol of iron atoms = 12.0 g

10.1 The Mole: A Measure-ment of Matter

38

>

39 of 50

Molar Mass

The molar mass of an element contains 1 mol or 6.022 × 10²³ atoms of that element.
1 mole of an element has the mass listed on the periodic table

.

The Mass of a Mole of an Element

10.1 The Mole: A Measure-ment of Matter

39

>

40 of 50

How many atoms are contained in the molar mass of an element?

Describe how to calculate the molar mass of a compound.

.

10.1 The Mole: A Measure-ment of Matter

40

>

41 of 50

Molar Mass

To calculate the molar mass of a compound:

determine the number of grams of each element
then add the masses of the elements in the compound.

.

The Mass of a Mole of a Compound

10.1 The Mole: A Measure-ment of Matter

41

>

42 of 50

Molar Mass

Find the molar mass of SO₃

the mass of sulfur (S) is 32.1 g
The mass of three atoms of oxygen:

(O): 3 × 16.0 g = 48.0 g

Molar mass of SO₃ is 32.1 g + 48.0 g = 80.1 g
1 mole of SO₃ has a mass of 80.1 g.
This is the mass of 6.022 x 10²³ molecules of SO₃.

.

The Mass of a Mole of a Compound

10.1 The Mole: A Measure-ment of Matter

42

>

43 of 50

Molar Mass

.

The Mass of a Mole of a Compound

1 mol of paradichlorobenzene (C₆H₄Cl₂) molecules (moth crystals)

= 147.0 g

1 mol of water (H₂O) molecules = 18.0 g

1 mol of glucose (C₆H₁₂O₆) molecules (blood sugar)

= 180.0 g

10.1 The Mole: A Measure-ment of Matter

43

>

44 of 50

The decomposition of hydrogen peroxide (H₂O₂) provides sufficient energy to launch a rocket. What is the molar mass of hydrogen peroxide?

.

Sample Problem 10.4

Calculating the Molar Mass of a Compound

10.1 The Mole: A Measure-ment of Matter

44

>

45 of 50

.

Add the results.

mass of 1 mol H₂O₂ = 2.0 g H + 32.0 g O = 34.0 g

molar mass of H₂O₂ = 34.0 g/mol

Sample Problem 10.4

Calculate Solve for the unknown.

2

10.1 The Mole: A Measure-ment of Matter

45

>

46 of 50

Find the molar mass of PCl₃

.

10.1 The Mole: A Measure-ment of Matter

46

>

47 of 50

What is the mass of 1 mole of sodium carbonate?

.

10.1 The Mole: A Measure-ment of Matter

47

>

48 of 50

What is 1 mole of:

Apples?

Write a brief set of directions on how to calculate the molar mass of any compound.

.

10.1 The Mole: A Measure-ment of Matter

48

>

49 of 50

END OF 10.1

.

10.1 The Mole: A Measure-ment of Matter

49

>

50 of 50

Glossary Terms

mole (mol): the amount of a substance that contains 6.02 × 10²³ representative particles of that substance
Avogadro’s number: the number of representative particles contained in one mole of a substance; equal to 6.02 × 10²³ particles
representative particle: the smallest unit into which a substance can be broken down without a change in composition, usually atoms, molecules, or ions
molar mass: a term used to refer to the mass of a mole of any substance

.

10.1 The Mole: A Measure-ment of Matter

50

>