Page 26
Testing Samples for Total Hardness
6200018bench.fm
Section 5
5.3.2 Total Hardness Buret Method
1.
If a buret is used, fill
a 25-mL buret with
Reagent 3.
2.
Refer to
Table 11
to
choose the size of the
volumetric pipet,
depending on sample
concentration.
3.
Using the volumetric
pipet, transfer the sample
volume from
Table 11
into a
clean 250-mL Erlenmeyer
flask.
4.
Dilute to about the
100-mL mark with
deionized water,
if necessary.
5.
Using a marked
dropper, add 1 mL of
Reagent 1.
Swirl to mix.
6.
Using a graduated
cylinder, add 8 mL of
Reagent 2. Swirl to mix.
Note: Prepare Reagent 2 by
mixing one bottle of Indicator
Powder into 1 L of Buffer
Solution. Reagent 2 can be
kept for approximately 3
months.
7.
Swirl the flask while
titrating with Reagent 3
from red to pure blue.
8.
Record the volume
required.
9.
Calculate the sample
concentration using the
equation below:
Refer to Table
11 on page 24.
FILL LIN
E
FILL LIN
E
Sample Concentration mg/L as CaCO
3
(
)
100000
Volume Required mL
(
)
×
Reagent 3 titer M
( )
×
Sample Volume mL
(
)
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=
