Chap 35 small.doc
Page
1
3.5
Fundamentals of Solution Stoichiometry
Molarity (
M
)
= moles of solute per volume of solution in liters:
M
=
molarity
=
moles of solute
liters of solution
=
moles
L
for instance
6 moles of HCl
2 liters of solution
=
3
M
HCl
(we say a 3
molar
solution)
1)
Preparing a solution:
If you weigh out
5.844 g of NaCl (MW or
M
= 58.44 g/mole) and dissolved it in
500. mL of water, what is the
molarity
of the solution?
a)
g
>
moles
5.844 g
x
1mole
58.44 g
=
0.1000 moles
b)
mL
>
L
500. mL
x
1 L
1000 mL
=
0.500 L
You do not have to show me this step now.
One can
simply move the decimal point 3 places to the left
, in going
from mL to L.
Conversely one can go from L to mL by
moving the decimal point 3 places to the right.
Just keep in
mind there will always be more mL than L because they are
the smaller unit!
c)
M
=
0.1000 moles
0.500 L
=
0.200 M
pronounced
molar
also symbolized with M
or
M
Note that your calculator only says 0.2.
It is your
responsibility to put in the
0.200
!
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 Fall '08
 Okamura
 Molarity, Mole, Stoichiometry, Moles, 0.200 M, 0.100 L, 0.057 L

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