Once a year, EWAT group gives a lecture in electrochemistry to undergraduate students from the faculty of Civil and Environmental Engineering at NUS.

The best way to explain electrochemistry is carrying out simple experiments during the lecture. Here, we are showing the electrolysis of water in a solution containing phenolphthalein (an indicator sensitive to pH changes). During the electrolysis of water we generate oxygen and hydrogen, can you guess what else is being generated?

The answer is: -OH and H+, causing a local change of pH in the vicinity of the electrodes, which develops a pink coloration.

If you want to do the experiment at home, you only need:

  • a battery
  • 2 pencils
  • salt (1 spoon)
  • pH indicator (few drops, get it at any aquarium shop)

Mix the salt and pH indicator in water, connect each pencil to the negative and positive terminal of the battery, immerse them in the water solution, done! electrolysis in action!