Hanna Instruments HI931 - Neutralization with Sodium Hydroxide

19
NEUTRALIZATION WITH SODIUM HYDROXIDE
NEUTRALIZATION WITH SODIUM HYDROXIDE
0 to 200 meq/L
METHOD ID: HI1009EN
DESCRIPTION
Method for the determination of strong or weak acid concentration by
titration of a sample to the equivalence point with sodium hydroxide.
The results are expressed as meq/L.
ELECTRODE
• HI1131B Combination pH Electrode
• HI7662-T Temperature Probe
REAGENTS
• HI70456 0.1N Sodium Hydroxide (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 Beakers (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 0.1N sodium hydroxide
(HI70456) 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 0.1N
sodium hydroxide, follow HI0001EN 0.1N Sodium Hydroxide
Titrant Concentration.
• Press from the main screen. Use the arrow keys
to highlight HI1009EN Neutralization w/NaOH 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 sensor and stirrer from
the sample and rinse them thoroughly with deionized water.
• Record the result.