The Mole

• Chemistry
• Secondary Education

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Reminders

• Prepare your device.
• Open Google Classroom.
• Join LessonUp.com =  code: 239 355
• Prepare your calculator.

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Topic 8 - The Mole and the Avogadro Constant

The Mole and Chemical Calculations

26 November 2025

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In this lesson, I will:

• state what a mole (in chemistry) means.
• use the relationship: amount of substance (mol) = mass (in g) / molar mass (in g/mol) to calculate:
• (a) amount of substance
• (b) mass
• (c) molar mass

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How many particles are there in one mole of oxygen gas?

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External Video

How many particles are there in one mole of oxygen gas?

What does the term "DOZEN" mean?

1. 6
2. 12
3. 24
4. 15

What does the term "DYAD" mean?

1. 2
2. 4
3. 6
4. 8

What does the term 

"A DOZEN DOZEN" mean?

1. 12
2. 24
3. 144
4. 0

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How many particles are there in...

602,000,000,000,000,000,000,000

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How many particles are there in...

602,000,000,000,000,000,000,000

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How many particles are there in...

602,000,000,000,000,000,000,000

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How many particles are there in...

602,000,000,000,000,000,000,000

How many particles are there in 4 grams of helium gas?

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602,000,000,000,000,000,000,000

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602,000,000,000,000,000,000,000

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The Mole

Mole, mol, is the unit of amount of substance, and one mole contains 6.02 × 10²³ particles, e.g. atoms, ions, molecules; this number is the Avogadro constant.

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The Ar or Mr of a substance, weighed out in grams, is known as one mole of that substance.

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The Ar or Mr of a substance, weighed out in grams, is known as one mole of that substance.

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The Ar or Mr of a substance, weighed out in grams, is known as one mole of that substance.

12g of carbon = 1 mol

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The Ar or Mr of a substance, weighed out in grams, is known as one mole of that substance.

12g of carbon = 1 mol

12g per mol

Molar Mass = "mass of one mole"

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The Ar or Mr of a substance, weighed out in grams, is known as one mole of that substance.

24g of magnesium = 1 mol

24g per mol

Molar Mass = "mass of one mole"

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23g + 35.5g of NaCl = 58.5g

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23g + 35.5g of NaCl = 58.5g

58.5g of NaCl = 1 mol

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23g + 35.5g of NaCl = 58.5g

58.5g per mol

Molar Mass = "mass of one mole"

58.5g of NaCl = 1 mol

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Amount of substance  (Symbol: n)

example:       n = 1 mol

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Amount of substance  (Symbol: n)

example:       n = 1 mol

unit of measure

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Molar Mass  (Symbol: M)

Amount of substance  (Symbol: n)

example:       n = 1 mol

example:      M = 24 g/mol

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Molar Mass  (Symbol: M)

Amount of substance  (Symbol: n)

Mass  (Symbol: m)

example:       n = 1 mol

example:      M = 24 g/mol

example:      m = 24 g

example:      m = 24 g

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x

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How many moles are there in:

• 4g of hydrogen (H₂)
• 36g of carbon atoms (C)
• 160g of ozone (O₃)

Known

Unknown

Workout

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Unknown

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Unknown

Workout

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What is the mass of:

• 0.1 moles of copper oxide (CuO)
• 2 moles of water
• 10 moles of ammonia (NH₃)
• 0.2 moles of ethane (C₂H₆)

Known

Unknown

Workout

Known

Unknown

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Known

Unknown

Workout

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Work in groups:

• Draw one option for your team.
• Solve the word problem together.
• Write your KUW on your whiteboard.
• Teach others: 2 members from your team will explain your work to other teams.

In this lesson, I will:

• state what a mole (in chemistry) means.
• use the relationship: amount of substance (mol) = mass (in g) / molar mass (in g/mol) to calculate: (a) amount of substance (b) mass (c) molar mass

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Assesses student comprehension through a worksheet, quiz, a lab report, or a concluding class discussion.

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