Mini Electrolysis Device

Quick Answer: The mini electrolysis device is a compact kit for electrolysing water on a student bench. The listing photo shows a small clear rectangular tank, an electrode block holding two small inverted collecting tubes, and red and blue leads with crocodile clips for connection to a low-voltage supply.

Electrolysis Scaled Down for Student Benches

A Hofmann voltameter is usually a teacher’s piece: tall, glass and clamped to a stand. The mini electrolysis device brings the same experiment down to a size each group can handle. In the photo a dark electrode block sits on the floor of a clear rectangular tank, two small tubes stand upright on it, one over each electrode, and a yellow clip on the tank wall anchors the red and blue leads.

Students fill the tank with dilute electrolyte, fill the two tubes and invert them over the electrodes, then connect the leads to a low-voltage DC source. Bubbles stream from both electrodes into the tubes, and the tube over the negative electrode fills with hydrogen about twice as fast as the other fills with oxygen. No power source appears in the photo, so plan for a battery pack or a laboratory power supply.

Compared with the Hofmann voltameter, the small tubes hold less gas and give a less precise volume comparison, so this device suits observation and gas testing more than measurement. For a jar-based demonstration with larger collecting tubes, see the Brownlee electrolysis apparatus.

Applications

• Small-group practicals on the electrolysis of water with dilute sodium sulfate solution
• Observing which electrode produces more gas and relating it to the formula of water
• Collecting a small tube of hydrogen for the lighted-splint pop test
• Showing how the supply voltage affects the rate of bubbling

Specifications

Care & Handling

• Connect the mini electrolysis device’s leads before switching the low-voltage supply on, and switch off before disconnecting.
• Wear eye protection when handling the electrolyte and emptying the tank.
• Rinse the tank, tubes and electrode block with water after each class and dry them before storage.
• Clean the clear parts with water and mild detergent only, since solvents can craze clear plastics.

Why Choose LabEquip

Teachers who want every group to run its own electrolysis, rather than watch a single demonstration, buy several mini devices as a class set. LabEquip lists them in its chemistry lab equipment range, and class-set numbers can be arranged through the contact page.

Frequently Asked Questions

Does the mini electrolysis device include a power supply?

No power source is shown in the listing photo, so plan to use a battery pack or a low-voltage DC laboratory supply connected with the crocodile clips.

Which tube collects hydrogen?

The tube over the electrode connected to the negative terminal, the cathode. It fills roughly twice as fast as the tube over the anode, where oxygen collects.

Why add sodium sulfate to the water?

Pure water has very few ions and barely conducts. Dissolving a little sodium sulfate adds ions to carry the current, while the products at the electrodes remain hydrogen and oxygen.

Can salt water be used instead?

Sodium chloride solution produces chlorine at the anode instead of oxygen. Chlorine is toxic, so salt water should not be used in this open student device.

How is this different from a Hofmann voltameter?

The mini device is compact and suited to groups working at their own benches. A Hofmann voltameter has long graduated tubes with stopcocks, so it gives more accurate gas volumes and easier gas testing.

Why does the bubbling slow down after a while?

Bubbles can cling to the electrodes and shield them, and battery supplies weaken under load. Tapping the tank gently and checking the supply usually restores a steady rate.

Last Updated: September 2026