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A DOZEN roses = 12 roses
A GROSS of pencils = 144 pencils
When you have a dozen of something, no matter what you are talking about, you
have 12 of that thing.
-A dozen donuts- a dozen eggs
-a dozen cars,
-a dozen chemistry problems are all 12 of that material.
The mole is the exact same concept. You can have:- a mole of eggs- a mole of donuts- a mole of cars- a mole of chemistry problems.
However a mole is MUCH bigger than 12
...it is 602 sextillion.
Obviously a mole of chemistry problems is way too many problems.
The mole is typically used for counting or grouping
very very small things, like
atoms
a MOLE (mol)
1. The mole is an SI unit that allows us to count # of:
- Atoms
- molecules
- formula units
without actually seeing them
Representative
particles
2. 1 mol = 6.02 x 1023
representative particles
3. The number is called “Avogadro’s number”
in honor of the Italian scientist
Amadeo Avogadro
Avogadro’s number
Atoms or
Molecules or
FUNs
1 mole of anything = 6.02 x 1023
4. REPRESENTETIVE particles:
1. ATOMs (elements on the PT)
2. MOLECULES (_______compounds –
all elements are non metals)
EX: CO2, NO2, C12H22O11
3. Formula Units (_____compounds – at least
one element must be a metal)
EX: NaCl, CuCl2, FeO
covalent
ionic
A DOZEN
MASS of a dozen limes = MASS of a dozen cars
A MOLE
CARBON COPPER
MASS of a mole carbon = MASS of a mole copper
6.02 x 1023 C atoms = 6.02 x1023 Cu atoms
HOW DO YOU DETERMINE
THE MASS OF A MOLE ?
MOLAR MASS – the mass of 1 mole of any pure substance (element and compound)
Molar Mass (MM) = Atomic mass (AM)
MM units - g/mol
AM - Atomic Mass units - amu (atomic mass units)
EX: Mn - 54.94 amu = 54.94 g/mol
EXAMPLES:
1. 1 mole of Al :
2. 1 mole of CO2:
AM (C) = 12.011 amu = MM
# of atoms = # of moles
AM (O) = 16.00 amu x 2 = MM
12.011 + 2 (16.00) = 44.01 g/mole
AM 26.98 g = MM 26.98 g/mol
3. 1 mole of Cu(NO2)2:
AM (Cu) 63.546 amu = MM g/mole
AM (N) 14 x 2 amu = MM g/mole
AM (O) 16 x 4 amu = MM g/mole
63.546 + 2(14) + 4 (16) = 155.5 g/mole
