General Instructions - 3B SCIENTIFIC PHYSICS U11335 Manual De Instrucciones

4. Technical data
Measurement ranges:
Sensor type:
Cell constant:
Max. operating
temperature:
Housing:
5. Operation

5.1 General instructions

•
Rinse the lower end of the electrode
thoroughly with distilled water, shake off any
remaining water and dry with filter paper.
•
Select the expected measurement range for the
test liquid by pressing the appropriate
measuring range button.
•
Immerse the end of the electrode with the slot
at its tip into the liquid to be tested.
Important: the graphite cell surfaces must be
completely immersed in the test liquid.
•
Stir the liquid gently with the electrode, and
after 5 to 10 seconds read the measured value.
•
When switching over to show the temperature
of the test liquid, the chosen measuring range
button must be held down for at least 2
seconds.
•
Wait for a new display to appear on the 3B
TM
NETlog unit ("Probe Detect") and read off the
temperature.
•
Press the appropriate measuring range button
again to return to conductivity measuring
mode.
•
Before making another measurement in a
different liquid, wash the electrode again in
distilled water and repeat the steps described
earlier.
•
The measurement system is suitable for a
temperature range from 15°C to 35°C. The
calibration temperature is about 25°C.
5.2 Calibration
The electrode is supplied pre-calibrated and ready
for use. Recalibration can only be carried out at
present by the manufacturer 3B Scientific GmbH.
0.2 mS/cm, 2 mS/cm,
20 mS/cm
4-cell graphite electrode
("Bull's Eye" four-wire
design), integrated Pt100
temperature sensor
K = 0.45/cm
80°C
epoxy resin, 120 mm x
19 mm diam.
5.3 Cleaning and care of the electrode
•
If electrodes get polarised or dirty they must be
cleaned using hot water and a mild detergent.
•
Organic substances should be removed with
acetone. Algae, bacteria, mould or mildew
should be removed with a solution of sodium
hypochlorite.
•
Do not use abrasives or objects that can scratch
the surface.
•
Finally, wipe the electrode with a cotton cloth.
6. Experimental applications
Distinguishing qualitatively between substances
with ionic or molecular structures in liquids, e.g.
dilute solutions of acids and alkalis.
Demonstrating the direct relationship between
conductivity and ion concentration in liquids.
Measuring ion
solutions.
Measurements of conductivity for photosynthetic
processes in a basin containing aquatic plants, and
observing the
bicarbonate ion concentration.
In-situ measurements of total quantities of
dissolved solids (TDS, in mg/l) in lakes or streams.
Observing rates of chemical reactions involving the
uptake or release of a conducting substance.
Conductivity changes in titrations with two
substances in stoichiometric quantities.
Measurements of the rate of diffusion of one type
of ion through a membrane (osmosis).
Measurements of conductivity and total dissolved
solids in an aquarium containing aquatic plants
and animals such as fish. Distinguishing between
photosynthesis and respiration
7. Sample experiments
The increase in the conductivity of distilled
water when common salt is added.
Equipment required:
TM
1 3B NETlog unit
1 Conductivity sensor
1 Glass beaker, 600 ml, shallow form
1 Set of Scout Pro electronic scales, 200 g U42048
1 Carton of table salt (500 g approx.)
1 Petri dish
1 Teaspoon
300 ml distilled water
2
concentrations in unknown
simultaneous reduction
U11300
U11335
U14210
of