Question

Many demonstrations of electrolysis show the use of baking soda and a 9 volt battery for electrolysis of water. As a science experiment, I tested different voltages by adding more batteries. In my experiment, I used distilled water. After letting the electrolysis happen for 5 minutes, the 18 volt test had yellow discoloration in the water. Because I couldn't find any places online that mention this or explain what it is, I thought to ask. Perhaps it is not a common thing?

Answer 1

Yellow discoloration in water during electrolysis may be due to the production of other chemical species, contamination, corrosion of electrodes, or abnormal chemical reactions caused by higher voltage applied.

Step-by-step explanation:

Understanding Electrolysis Discoloration

During the electrolysis of water, the application of a sufficient net voltage is necessary to induce the decomposition of water into hydrogen and oxygen gases. For an effective electrolysis process using distilled water, a small amount of an ionic solute, such as H₂SO₄ (sulfuric acid) or Na₂SO₄ (sodium sulfate), is typically added to increase the water's electrical conductivity. When a voltage of about 1.7-1.9 V is applied between inert electrodes, hydrogen is produced at the cathode and oxygen at the anode.

If yellow discoloration occurred during your experiment, it might be due to the electrolytic production of other chemical species, possible contamination, or corrosion of the electrodes. Using distilled water without added electrolytes can lead to low conductivity and inefficiency, but it shouldn't cause significant discoloration unless impurities are present. It is also possible that the higher voltage caused more intense conditions that led to abnormal chemical reactions or the production of colored substances not typically observed at lower voltages.