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Science Lab Experiment: Electrolysis

Demonstration: Electrolysis

Object: To separate water into its elements.

Materials: sulfuric acid (H2SO4), Hoffman apparatus, 9-volt battery, stand and clamp, test tube, wooden splint


Method: The materials were set up as shown in the diagram. Some sulfuric acid was mixed with the water to improve the condition of electricity. The Hoffman apparatus was connected to a 9-volt battery.

Observations: Bubbles were observed in the two outer tubes of the apparatus when the battery was connected. After a half hour the volumes of the gasses in the outer tubes were compared and tested. The volume in the tube connected to the negative terminal of the battery was found to be twice the volume of the gas in the tube connected to the positive terminal of the battery. When tested with a burning splint the gas with twice as much volume "popped", showing that it was hydrogen. The other gas burned, proving it was oxygen.

Conclusions: Electricity will separate water into hydrogen and oxygen. Hydrogen, as a positively charged element, is attracted to the negative electrode. Oxygen, as a negatively charged element, is attracted to the positive electrode.