The Mole – It’s Important

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The Mole – It’s Important. Buying Eggs. When you buy eggs, you usually ask for a dozen eggs. (12) You know that one dozen of ANY item is 12. Paper Packages. Paper is packaged by a ream. One ream of paper is equal to 500 sheets .

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### The Mole – It’s Important

• When you buy eggs, you usually ask for a dozen eggs. (12)
• You know that one dozen of ANY item is 12.
Paper Packages
• Paper is packaged by a ream. One ream of paper is equal to 500sheets.
• You know that if you have 2 reams of paper, you have 1000 sheets.
Group Brainstorm
• If you were asked to create a new unit to count something, what would you consider when choosing how many items should be included in your new counting unit?
• What kinds of things would you pay attention to when you were going to make this unit?
The Problem
• Chemists and scientists had this exact problem when they were trying to decide how to count atoms.
• Recall that atoms are the basic building blocks of matter, and that they are incredibly small. More atoms than you can count in a million years are present in a grain of sand.
A Solution!
• In 1815, a man named Amadeo Avogadro came up with a solution.
• He realized that he needed a unit that would make it convenient to weight out certain amounts of different elements.
• After a lot of complicated work he came up with this...
The Mole!

The mole is the unit that we use to count atoms!!!!

What is the Mole?
• Remember that this concept is NO DIFFERENT from the fact that a dozen of something is 12 of that thing;
• A mole of something is 6.022 x 1023, a.k.a.

602 200 000 000 000 000 000 000

of something.

• This massive number (6.022 x 1023) is also known as Avagadro’s Number, since he is the one who defined it.
• Technically, a mole is the number of atoms in 12 grams of Carbon-12. All we need to know is that the mole is super convenient.
Just How Big is a Mole?
• Enough soft drink cans to cover the surface of the earth to a depth of over 200 miles.
• If you had Avogadro's number of un-popped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles.
• If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years to count the atoms in one mole.

• 1 dozen cars = 12 cars
• 1 mole of cars = 6.02 X 1023 cars
• 1 dozen Al atoms = 12 Al atoms
• 1 mole of Al atoms = 6.02 X 1023 atoms

Note that the NUMBER is always the same, but the MASS is very different!

Mole is abbreviated mol

Some Examples:
• You have 3 moles of soccer balls. How many soccer balls do you have?
• I have 5.46 x1028 ballerina shoes, how many moles of them do I have?

Do you have any questions about the mole?

The Periodic Table Gets It...

This is the mass of ONE MOLE of carbon atoms. It is also known as the MOLAR MASS of carbon.

1 mole of C atoms = 12.0 g

1 mole of Mg atoms = 24.3 g

1 mole of Cu atoms = 63.5 g

1 mole of CaCl2 = 111.1 g/mol

1 mole Ca x 40.1 g/mol

+ 2 moles Cl x 35.5 g/mol = 111.1 g/mol CaCl2

1 mole of N2O4 = 92.0 g/mol

Calculations with Molar Mass

molar mass

Grams Moles

Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al?

3.00 moles Al ? g Al

1. Molar mass of Al 1 mole Al = 27.0 g Al

2. Conversion factors for Al

27.0g Al or 1 mol Al

1 mol Al 27.0 g Al

3. Setup3.00 moles Al x 27.0 g Al

1 mole Al