Electrolytes and conductivity
To introduce the concept of electrolytes and conductivity, and to check electric current by means of an electric light bulb.
What students learn
The science behind this experiment
Electrolytes are substances that dissolve in water producing ions which conduct electrical current. Non-electrolytes are substances whose aqueous solutions do not contain ions and hence do not conduct an electric current.
Conductivity is the ability of a substance, solid, liquid or gas, to carry an electric current. Conductivity is measured in.
Equipment used
- DC power supply
- Connecting wires, red — 2522.03-04
- Connecting wires, black — 2522.04-08
- Copper electrodes — 4716.21
- Crocodile clips — 2531.52
- Test cell covers — 4718.10
- Beaker 50 ml — 1118.15
- Lamp holder — 2505.50
Chemicals and reagents
- Distilled water
- Sucrose solution
- Hydrochloric acid solution 1 M — R:34-37 S:26-45
- Acetic acid solution 1 M — R:10-35 S:23-26-45
- Sodium chloride solution 1 M
- Sodium hydroxide solution 1 M — R:35 S:26-37/39-45
Safety notes
- Be careful when using the power supply and conductive solutions: risk of electric shock.
Questions for students
- Note the current intensity by watching the brightness of the light bulb.
- Classify the electrolytes according to your observations.
What to expect
<p>Electrolytes are classified either as strong electrolytes or weak electrolytes. Strong electrolytes when dissolved in water dissociate completely to produce ions.</p><p>Solutions of strong electrolytes are good conductors of electricity because they contain a relatively high concentration of ions.</p><p>Weak electrolytes are only partially converted to ions in aqueous solution. Ethanoic (acetic) acid, CH3CO2H, the active ingredient of vinegar, is a weak electrolyte.</p><p>Only about 1% of the dissolved ethanoic (acetic) acid molecules are converted to ions. The rest remain unchanged. Thus, a solution of a weak electrolyte contains a relatively low concentration of ions and its conductivity would be expected to be low.</p><p>Distilled water and sugar solutions do not conduct an electric current. Sugar is not an electrolyte.</p>
Disposal
Dispose of the solutions into the waste container.
Run this experiment in your classroom
This experiment is part of the ATP Mobile Lab — a self-contained laboratory that turns an ordinary classroom into a working science lab, with over 200 experiments in physics, chemistry, biology, robotics and engineering. Gali, the AI tutor built into ATP Connect, guides students through each step and answers their questions at the bench.
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