Transcript Dimensional Analysis and the MOLE!!!!!

Unit 1 continued
The Mole!!!
Intro to the Mole
 Counting by Mass
 The Mole
 Molar Mass
Counting Candy: Counting by
Mass
 Sometimes it is inconvenient or even impossible to
count using traditional methods
 Small particles
 Large numbers of particles
 Counting by mass uses the average mass of the
particle to calculate a given number of particles
 How much candy is in my jar?
 Get an average mass (massA)
 Get a total mass (masst)
 # particles = masst/massa
Atomic Masses and the Mole
 You can calculate the
given number of atoms
using the atomic mass
 Atomic mass expressed
in AMU’s is the mass of 1
atom of that element
 Atomic mass is the
weighted average mass
of all the isotopes of an
atom
 The atomic mass
expressed in grams is
the mass of 1 mole of
atoms
…So, what is a mole?
The Mole
 Suppose we have a sample
of Al with a mass of
26.98g
 What mass of Cu would
have the same number
of atoms?
 How about C?
 If we were to measure out
samples of any elements
such that the masses in
grams are equal in number
to the atomic masses, we
will ALWAYS have the
same number of atoms!
THAT NUMBER IS
CALLED…THE
MOLE!
More Mole
 The Mole: the number equal to the
number of carbon atoms in 12.01g of
carbon.
 It is associated with a specific number:
Avogadro's Number
 6.022x1023 of anything is a mole
 Think “dozen”
 It is a UNIT!
Molar Mass = mass of 1 MOLE
 Element: The molar
mass of an element is
equal to the atomic mass
expressed in grams
instead of AMU’s
 What is the Molar Mass
of
 Carbon
 Compound: The molar
mass of a compound is
equal to the sum of the
molar masses of each
element in the compound
in the correct ratio.
 Calculate the molar mass
of:
 Nickel
 CO2
 Oxygen (careful
diatomic!)
 NaCl
 Pb2(SO4)3
Picture of Molar Mass
A little help please (mole problem
flow chart)
Practice!
 Calculate the Number
of particles
(atoms/molecules) in:
 2.5 mols Na
 Calculate the mass of:
 1.0 mols CH4
 76 g K
 6.022x1023 atoms
of Na
 23 g CO2
 2.4 mols PbNO3
 1240 mg HBr
 2.3x1022 mlcs
H2SO4
More Practice!
 Calculate the molar
 Perform the following
mass of the
calculations:
following:
 1.0 moles O2  particles O2
 Molybdenum
 Lanthanum
 2.6 g Cu  moles Cu
 CBr4
 4.0x1022 atoms Al  moles Al
 HgO
 4.0x1022 atoms Al  grams Al
 TiO2
 26.2g NaCl  moles NaCl
 MnCl2
 PH3
 26.2 g NaCl  particles NaCl
End the Mole Madness!
 Tips to help with mole problems…
 In the conversion process, the mole gets a 1
 6.022x1023 will ALWAYS be atoms, particles,
etc.
 Use the molar mass any time you see grams
 Let your units tell the story