# Mole _2_.ppt by changcheng2

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```									  Chemistry
5072
Mass of 1 atom
• What is the mass of 1 proton?
1.67 X 10-24g
o What is the mass of 1 neutron?

1.67 X 10-24g
o   What is the mass of one Hydrogen atom?

1.67 X 10-24g
Because hydrogen atom has only one proton
Mass of 1 atom ctd…
• What is the mass of 1 carbon atom?
12 X 1.67 X 10-24g
o   What is the mass of 1 sodium atom?

23 X 1.67 X 10-24g
Molar mass
4                            32
2   He                       16   S

24                             12
12   Mg                         6   C

Let’s take the mass number as the mass in gram, how many atoms
are there? (i.e. how many atoms are there in 4g of He?)
• Well, you know that given the mass
number in grams, there are 6 X 1023
atoms/particles.
• 6 X 1023 is a constant number and this is
• 4g of He, 32g of S, 24g of Mg and 12g of
C contain 6 X 1023 particles. The mass
which gives 6 X 1023 particles is termed
as Molar mass!
Mole
• One mole of any substance contains 6 X
1023 of particles.
• Therefore, molar mass of Na is
23g/mol.
• How about molar mass of:
a)Zn
b)Si
c)Ar
d)Ca
Analogy

Mass of 1 orange = mass of 1 apple = 10g

If the basket can contains 2 apples and 2 oranges,
40g
what is the mass of the basket now?

If one container can take in 10 baskets,
what is the mass of the container?                   400g
Analogy ctd…

Mass of 1 orange = mass of 1 apple = 10g

If the basket can contains 5 apples and 5 oranges,
100g
what is the mass of the basket now?

If one container can take in 10 baskets,            1000g
what is the mass of the container?
Analogy
proton                                                           neutron

nucleus

Mass of 1 orange = mass of 1 apple = 10g                  Mass
Mass of basket = 0g                           number

If the basket can contains 2 apples and 2 oranges,
what is the mass of the basket now?              40g

If 1 container can take in 10 baskets,                    Molar
what is the mass of the container?                        mass
400g
Mole
• 1 mole of any substance contains 6 X 1023
particles.
• How many particles are there in 2 moles of
Na?
1.2 X 1024 particles of Na
o How many particles are there in 3 moles of
C?
1.8 X 1024 particles of C
o How many particles are there in 0.25 of Ti?
1.5 X 1023 particles of Ti
Mole ctd…
• If there are 4 X 1023 particles of Mg, how
many moles of Mg are there?
4 X 1023 particles = 0.667 moles (3 sf)
6 X 1023 particles
• If there are 1.5 X 1022 particles of He, how
many moles of He are there?
1.5 X 1022 particles = 0.0250 moles (3 sf)
6 X 1023 particles
Number of
particles

X (6X1023)          ÷
(6X1023)

Mole

```
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