Hanna Instruments HI931, User Manual

Page: 187 / 218

17
NEUTRALIZA
TION WITH SULFURIC ACID
NEUTRALIZATION WITH SULFURIC ACID
0 to 200 meq/L
METHOD ID: HI1008EN
DESCRIPTION
Method for the determination of strong or weak base concentration by
titration of a sample to the equivalence point with sulfuric acid. The
results are expressed as
meq/L .
ELECTRODE
• HI1131B Combination pH Electrode
• HI7662-T Temperature Probe
REAGENTS
• HI70459 0.05M Sulfuric Acid (1 L)
• HI70436 Deionized Water (1 gal)
ACCESSORIES
• HI70300L Storage Solution (500 mL)
• HI7082
Electrode Fill Solution (4 x 30 mL)
• HI7004L pH 4.01 Buffer Solution
• HI7007L pH 7.01 Buffer Solution
• HI7010L pH 10.01 Buffer Solution
• HI740036P 100 mL Plastic Beaker (10 pcs)
• 10 mL Class A Volumetric Pipette
DEVICE PREPARATION
• Connect the pH electrode and temperature probe to the titrator.
• Install a 25 mL burette filled with 0.05M sulfuric acid (HI70459)
on pump one and verify that no air bubbles are present in the
burette or tubing. If necessary prime the burette until all the air
has been removed completely.
• For the determination of the exact concentration of the 0.05M
sulfuric acid, follow
HI0103EN 0.05M Sulfuric Acid
Titrant
Concentration.
• Press from the main screen. Use the arrow keys
to highlight
HI1008EN Neutralization w/H2SO4
and press
.
ELECTRODE PREPARATION
• Press from the main screen, if necessary select the
analog board and press .
• Calibrate the electrode using pH 4.01, 7.01 and 10.01 buffers.
Refer to the instruction manual for calibration procedure.
SAMPLE PREPARATION
• Use a class A volumetric pipette to transfer exactly 10.00 mL of
sample to a clean 100 mL plastic beaker.
• Add deionized water to the 50 mL mark on the beaker.
ANALYSIS
• Place the beaker under the stirrer assembly and lower it to
immerse the pH electrode, temperature probe and stirrer. Ensure
that the reference junction of the pH electrode is 5 to 6 mm
below the surface.
Note : The dispensing tip should be slightly submerged in the
sample.
• Press , the titrator will start the analysis.
• At the end of the titration, after detection of the equivalence
point, “Titration Completed” will appear with the result. The
result is expressed in
meq/L.
• Remove the pH electrode, temperature probe and stirrer from the
sample and rinse them thoroughly with deionized water.
• Record the result.