3B Scientific pH Sensor - Manual (Page 5)

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4. Technical data
Measurement range: pH 0 to pH 14
pH at zero voltage: pH 7.00 ± 0.25
Sensor type: Ag-AgCl combination elec-
trode, gel-filled, non-
refillable
Accuracy: pH 0.05 in the range from
20°C to 25°C
Resolution: pH 0.01
Reaction time: ≤ 1 s for 95% of final value
5. Operation
• Remove storage bottle from the electrode by
twisting off the lid, then pull the lid off the elec-
trode.
• Rinse the lower end in the vicinity of the glass
bulb thoroughly with distilled water, shake off
remaining water and dry with filter paper.
• Move air bubbles in the lower part of the elec-
trode chamber into the upper part by cautiously
shaking them downward.
• Calibrate the electrode. For the procedure, see
section 6 “Calibration”.
• Subsequently, rinse with distilled water, shake off
remaining water and dry with filter paper.
• Conduct measurement.
• After finalising the measurement, rinse the elec-
trode with distilled water and repeat the same
procedure as before the measurement.
• Slide the lid on the electrode and tighten it to the
storage bottle.
6. Calibration
• Connect the electrode to the sensor box, and
connect the sensor box to analog input A of the
3B NETlog
TM unit, analog input B is suitable for
pH-measurement but not for calibration!
• Wait for the “Probe Detect” function to detect the
sensor.
• Press the (Date/Time
↵) key 4 times until “User
Calibration” appears in the display.
• Start calibration by pressing the (Store L) key.
• Immerse the electrode (after rinsing) in the alka-
line “pH 9.00 buffer solution”.
• Move the decimal points in the display of the (SET
1) with the (Channel
I) key towards the left or
with the (Date/Time
↵) key to the right, respec-
tively.
• Increase the displayed value with the (Rate K) key,
or decrease it with the (Store L) key, respectively.
• Set the displayed value to +9.000e+00 and press
(Date/Time
↵).
• Wait for the correction of the measured value,
press (
J ACCEPT) and validate with the
(Date/Time
↵) key.
• Remove the electrode from the “pH 9.00 buffer
solution”, rinse and dry thoroughly, and immerse
in the “pH 4.00 storage solution”.
• Repeat the procedure described above for (SET 2).
• Wait for the “Probe Detect” function to detect the
sensor then conduct the desired measurements.
7. Cleaning the electrode
• After prolonged periods of use, clean the elec-
trode for 1 to 2 minutes in dilute hydrochloric
acid HCl (0.1 mol), then rinse with distilled water
and rejuvenate in potassium chloride KCl (4 mol).
8. Use in experiments
Measurement of common household acids and alkalis
Acid-base titrations
Observation of pH changes in chemical reactions
Testing the influence of photosynthesis on water qual-
ity in aquaria
Examining the influence of acid rain and its neutrali-
sation
Water quality of rivers and lakes
9. Sample experiment
9.1 Qualitative determination of the titration
curve of vinegar
Required equipment:
1 3B NETlog TM U11300
1 pH Sensor U11350
1 Measuring cylinder, 100 ml U14205
Household vinegar pH 2.00
Highly dilute sodium hydroxide pH < 14.00