Intro Questions:
Write these questions down on a separate sheet of paper so that at
the end of class you can answer the questions and hand your
responses in to the teacher
1. What are three methods of measuring the amount of matter?
2. How is Avagadro’s number related to the mole of a substance?
3. How is atomic mass related to the mole?
4. How is the mass of a mole of a substance calculated?
5. For what purpose, do we use the expanded mole diagram?
Three ways to measure Matter
1. Count
2. Mass
3. Volume
Count – Avagadro’s Number
Mass – Atomic mass
Volume – 22.4 L
First We Count:
Avagadro’s number is a specific quantity
or count of representative particles
which can be atoms, molecules, or
formula units
This number is 6.02 x 1023
This number is one mole – a mole is a
specific quantity of matter like a dozen
eggs or a cup of milk it signifies a
quantity of matter
So, How much is 6.02 x 1023?
6.02 x 1023 Watermelon Seeds: Would be found inside
a melon slightly larger than the moon.
6.02 X 1023 Pennies: Would make
at least 7 stacks that would reach
the moon.
6.02 X 1023 Blood Cells: Would be more
than the total number of blood cells found in
every human on earth.
1 Liter bottle of Water contains 55.5
moles H20
So what kind of particles does Avagadro’s number “count” in chemistry?
Lets make a list!
1.
2.
3.
How doe convert the particles counted to a mole?
Converting Number of Particles to Moles:
Representative Particles x __________1mole_____________ = moles
6.02 x 1023 representative particles
How many moles are in 2.80 x 1024 atoms of silicon?
How many moles are in 5.23 x 1018 molecules of water?
In the same way we can turn a number of moles in to some
type of particle.
Number of moles x
6.02 x 1023 particles = # of particles
1 mole
How many atoms are in 1.14 moles of Na?
How would you find the number of atoms in 2.5 moles of water?
Remember
particles -------------- moles
particles
moles ------------------ particles
moles
Second We Find Mass:
There is a relationship between the mole, Avagadro’s number,
and mass. The atomic mass of an element expressed in grams
is the mass of a mole of the element. This is known as the
Molar Mass of the element.
That means is you have one mole of Na you have 6.02 x 1023
atoms of sodium that weighs 23g
Why 23g? Because one mole of any atom equals its atomic
mass in grams.
Try a few:
Mg, O, Cl, C, W
How would you calculate the molar mass of a compound like water?
Find the molar mass of NaCl
What would be the mass of 2 moles of NaCl?
Remember grams ------------ moles
moles-------------- grams
Third We find Volume
There is a relationship between one mole of any gas and a quantity
of that gas in liters.
1 mole of gas = 22.4 L
So how would we convert 55.2L of CL to moles?
Remember
Liters --------------- moles
Moles --------------- Liters
There are three ways to convert moles
1. Moles to particles
2. Moles to grams
3. Moles to volume
Likewise, you can reverse the process
1. Particles to moles
2. Grams to moles
3. Volume to moles
This type of converting is described in the expanded mole diagram
seen below. Now take out your expanded mole diagram and lets see
Lets make a list of the possible conversion displayed by the diagram.
Now turning to your test, lets try the sample problems 10.5 to 10.8
found on pages 298 – 302.
Now lets try the guided work-sheet. Do you see any patterns in your
work?
Homework – Section Questions 10.1 -10.2, worksheet, quick quiz on
mole conversions