Chapter 4 - Chapter
4
 Mole
 •...

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Unformatted text preview: Chapter
4
 Mole
 • Contains
6.022
×
1022
(Avogadro’s
number)
atoms,
molecules,
or
formula
units
 • Abbreviated
mol
 Molar
Mass
 • The
mass
of
one
mole
of
a
substance
 • Found
by
adding
the
atomic
masses
together
(H2O
H=1.01,
O=15.99,
so
H2O=18.01)
 • Abbreviated
MM
 Moles
from
Mass
 • When
you
are
given
the
grams
of
a
substance,
but
need
to
convert
to
moles
you
use
the
molar
 mass
(1.27g
Cu
×
 
 
 
 
=
0.0200
moles
Cu)
Note:
notice
that
the
proper
units
cancel
 Number
of
atoms,
 molecules,
or
 formula
units
 Mass
in
grams
 MM
 Moles
 Avogadro’s
 number
 Percent
Composition
by
Mass
 • An
expression
of
the
portion
of
the
total
mass
contributed
by
each
element
 • Found
by
dividing
the
part
by
the
whole
and
multiplying
by
100.

For
example:
To
find
the
 percent
of
1.27
g
Cu
in
a
3.67
g
sample
of
chalcopyrite
use
 
Cu
 Empirical
Formula
 • Expresses
the
simplest
ratios
of
atoms
in
a
compound
 • Written
with
the
smallest
whole
number
subscripts,
basically
reduce
by
the
largest
common
 denominator
(C5H10
becomes
CH2
but
H2S
remains
H2S
because
it
is
already
“reduced”)
 Empirical
Formula
from
Percent
Composition
 
 %
A
 Mass
of
compound
 Mass
A
 MM
of
A
 Moles
A
 Empirical
 formula
 
 
 
 
 Mass
of
compound
 
 MM
of
B
 %
B
 Mass
B
 
 Molarity
 • Most
common
way
to
express
concentration
 • The
number
of
moles
dissolved
into
one
liter
of
solution
 • Abbreviated
M
(note
the
italics)
 • Molarity
=
 

 
 Moles
B
 
 Molarity
of
Solutions
 
 
 Mass
from
Molarity
 
 Grams
of
solute
 MM
 Moles
of
solute
 volume
 Molarity
 Molarity
 volume
 Moles
of
solute
 MM
 Grams
of
solute
 
 Solution
 • • • • Solution
–
any
mixture
that
is
homogeneous
at
the
molecular
or
ionic
scale
 Solvent
–
the
substance
doing
the
dissolving
(usually
water)
 Solute
–
the
substance
in
a
solution
that
is
dissolved
into
solution
(usually
smaller
amount
than
 solvent)
 Dilute
vs
Concentration
–
dilute
solutions
contain
small
amounts
of
solute,
where
concentrated
 solutions
contain
large
amounts
of
solute
 Dilution
 • • The
process
of
lowering
the
concentration
of
a
solution
by
adding
more
solvent.
 Found
by
the
formula
M1V1=M2V2

 ...
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