1. Chemical Quantities 10.1 The Mole: A Measurement of Matter Chapter 10
10.2 Mole-Mass and Mole-Volume Relationships
10.3 Percent Composition and Chemical Formulas
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2. The Mole Concept Avogadro’s Number = 6.022 x 1023 Objectives:
To state the value of Avogadro’s number: x1023.
To state the mass of Avogadro’s number of atoms for any element by referring to the periodic table.
To relate the moles of a substance to the number of particles.
Avogadro’s Number = x 1023

3. CHEMISTRY & YOU
How can you quantify the amount of sand in a sand sculpture?
You could measure the amount of sand in a sculpture by counting the grains of sand. Is there an easier way to measure the amount of sand?
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4. Chemical Quantities
There are terms used to equate a certain quantity of matter
For example 1 dozen = 12, 1 Ton = 2,000 LBs and 1 gross = 144.
Before we get to the chemical terms lets convert between units we already know

5. For example – let’s say you want to buy some Bazooka Gum
You could buy it by the piece from the deli
You could buy it by the box from ShopRite
You could buy it by mass from the candy store

6. So, the different ways to measure Bazooka gum
1 dozen = 12 pieces
1 dozen = 1.75 boxes
1 dozen = 168 grams

7. Based on those conversions, I can determine how much Bazooka gum I have, regardless of how it is measured.
I have 95 pieces of Bazooka gum, how many grams do I have?

8. I have 95 pieces of Bazooka gum, how many grams to I have?

9. Do-Now
If I have 2 stadiums how many baseball bats do I want to purchase?
2 baseball players = 4 baseball bats
1 stadium = 18 baseball players
18 baseball players = 52 corn dogs

10. What Is a Mole?
What Is a Mole?
How do chemists count the number of atoms, molecules, or formula units in a substance?
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11. What Is a Mole?
Recall that matter is composed of atoms, molecules, and ions.
These particles are much, much smaller than grains of sand, and an extremely large number of them are in a small sample of a substance.
Obviously, counting particles one by one is not practical.
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12. Chemical Quantities
In chemistry, there are many way to measure the amount of substance
The count (quantity)
The volume (how much space it takes up)
The mass (the amount of matter)
Knowing how the count, mass, and volume of an item relate to a common unit allows you to convert among these units.

13. In chemistry, we do not use a dozen.
Since atoms are so small, we need a quantity with a larger amount
We use the mole (mol)
1 mole = X 1023 representative particles (atoms, molecules, formula units)
It is known as Avogadro’s number
Amedeo Avogadro

14. Amedeo Avogadro
An Italian chemist whose important contributions was his resolution of the confusion surrounding atoms and molecules. Avogadro believed that particles could be composed of molecules and that molecules could be composed of still simpler units, atoms. The number of molecules in a mole (one gram molecular weight) was termed Avogadro's number

15. We usually are dealing with three types of representative particles
Molecules
H2O and H2 are molecules, covalently bonded
Atoms
Al and Na are atoms, not bonded
Formula units
CaCl2 and NaOH are formula units, ionicly bonded

16. 1 mole of any representative particle is always 6.02 X 1023
Using this value we can convert between moles and atoms/ molecules/ formula units

17. For example: If a sample contains 0
For example: If a sample contains mol of O2, how many representative particles are present?
0.476 mol O2 x (6.022 x 1023 particles/1 mol O2) = x 1023

18. For example: If a sample contains 5
For example: If a sample contains X 1021 atoms of aluminum, how many moles are present?

19. Converting Number of Atoms to Moles
Sample Problem 10.2
Converting Number of Atoms to Moles
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?
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20. We can determine the molar mass of representative particles
Molar mass is the mass of 1 mole of that substance
The atomic mass is equal to the molar mass for an element
1 mol Na = g Na

21. For molecules and formula units, we must calculate the molar mass
Let’s calculate the molar mass of
SO3
S = 1 X = 32.07
O = 3 X = 48.00
= g/mol

22. We can use the molar mass of a substance to convert from moles to mass
Remember the molar mass is the mass of 1 mole of that substance
SO3 = g/mol = g SO3
1 mol SO3

23. Using this relationship, we can easily convert a mole amount to a mass amount
How many grams is there in a mole sample of SO3?

24. We can also convert a mass amount to a mole amount
How many moles is there in a 28.5 gram sample of SO3?

25. Key Concepts
The mole allows chemists to count the number of representative particles in a substance.
The atomic mass of an element expressed in grams is the mass of a mole of the element.
To calculate the molar mass of a compound, find the number of grams of each element in one mole of the compound. Then add the masses of the elements in the compound.
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