How to dilute a solution
How to Dilute a Solution
To prepare
N
units of a
C_{2}
% Concentration solution from
a
C_{1}_{ }%
solution, you need:
N
x C_{2}
%
_____________
units of
C_{1}_{ }%
solution
C_{1}_{
}%
For
required dilution:
Add calculated number of units of
C_{1}_{
}% solution to
(N
minus
calculated number
) oz.
of water, for a total of N
units of a
C_{2}
% solution
Special
note when diluting a violently reactive solution
– Eg. hydrochloric acid, it is
safer (contains somewhat violent reaction in a less full container)
to add half of
the required water before adding the
calculated number of required
units of
C_{1}_{ }%
solution, and then top up with the
rest of the water, for a total of
N
units
Example 1:
To prepare
N ( 8
oz.) of C_{2}
% (6 %) hydrochloric
acid from a
C_{1 }%
(32%) hydrochloric acid solution, you
need:
8
x
6
%
_____________
oz. of 32_{
}% solution =
1.5
oz.
_{ }32
%
You will be adding 1.5
oz.
32% hydrochloric acid to
6.5 (i.e.
8
 1.5
) oz.
of water
for a total 8
oz.
of 6%
solution of Hydrochloric acid
HOWEVER,
since HCl acid produces a somewhat violent reaction with water,
then first add 4
oz.
water, then 1.5
oz. 32
% hydrochloric acid, then finally top up with
2.5 (i.e.
8
minus 4
minus 1.5
) oz.
water
Example 2:
Make
100
ml
of a 3 % solution of hydrogen peroxide from
35% hydrogen peroxide:
You need:
100
x
3
%
_____________
ml of 35_{
}% solution = ~
8.5
ml.
_{ }35
%
Add
8.5
ml.
35 % hydrogen peroxide to
91.5
(i.e.
100
minus
8.5
)
ml.
water for a total of
100
ml. of a 3 % solution of hydrogen peroxide
