Transcript The Mole - Alliance Gertz

Subject:
Chemistry 1
The Mole and Avogadro’s number
(Notes)
a) How many atoms exist in a
molar Given:
mass 1of
amusubstance?
= 1.6605x10-24 g
H - Hydrogen
Mass of 1 H= 1.00 amu
= 1.00amu x 1.6605 x 10-24g/amu
= 1.6605 x 10-24 g/atom
# of atoms in 1.00 g of H= 1.00 g/1.6605 x 10-24g/atom =
= 6.02 x 1023 atoms
a) How many atoms exist in a
molar Given:
mass 1of
amusubstance?
= 1.6605x10-24 g
C - Carbon
Mass of 1 C= 12.0 amu
= 12.0amu x 1.6605 x 10-24g/amu
= 1.9926 x 10-23 g/atom
# of atoms in 12.0 g of C= 12.0 g/1.9926 x 10-23g/atom =
= 6.02 x 1023 atoms
b) Avogadro’s Number
Mr. Avogadro
If we use “gram” as the mass unit in
place of “amu” as in the Periodic
Table, the number of atoms is always
the same:
6.02 x 1023
This number is known as “Avogadro’s
number”. The amount of substance
involved is called a “mole”
c) The mole
= 1 Avogadro’s number of particles
A mole of H atoms is 1.0 grams of H
23 grams of
A mole of Na atoms is ____
Na.
2 moles of Na.
46 grams of Na is ____
c) The mole
A mole of H2O molecules is 18
of H2O
grams
.5 moles of H2O
9 grams of H2O is ____
2 moles of H2O
36 grams of H2O is ____
c) The mole
To calculate the number of moles, just
divide the mass by the molar mass
n = mass/molar mass
On October 23rd, at 6:02 Celebrate!
Happy Mole Day!