Electrolysis 2

Instead of using frog's legs to test whether electricity was produced, they were using a device developed by Nicholson, similar to the gold leaf electroscope. To get a better contact between the wires from their battery and the measuring device, they used a drop of water. When they noticed that a gas was bubbling off from this water, they investigated further and were astonished to find that when they passed the electric current from their battery through river water there was a reaction - a gas bubbled off from both wires they had dipped into their sample. That was the first time electrolysis was seen.

A few years later in 1807, potassium was discovered by Sir Humphry Davy whilst using electrolysis on molten potassium hydroxide. Later in the same year, he discovered sodium using the same method. The following year, he discovered barium, calcium, boron, strontium, and magnesium too. But it was the assistant of Davy who worked out the laws of electrolysis - Michael Faraday. These laws enabled scientists to predict and plan how much of each substance could be produced from electrolysis. He also introduced the terms used in electrolysis that you are familiar with such as anode, cathode, electrode, and ion (although they were actually invented by the Master of Trinity College, Cambridge, William Whewell).

Once electricity generating equipment had improved and electrolysis was better understood, the commercial value of the process was realized and it was taken up by industry. The first large scale electrolytic cells were developed in the 1880s for the electrolysis of brine which gave birth to the chlor-alkali industry. Also during the same decade, the Hall-Héroult process for the extraction of aluminum was developed which transformed aluminum from a rarely seen and extremely expensive metal into the cheap and widely used metal of today. There were no health and safety at work regulations at the time and workers in both industries could expect short lives due to the toxic and corrosive nature of the chemicals involved. For the high school, you should know how electrolysis works for both processes and the main uses of the products.

Have a go at this quiz and test your knowledge of electrolysis, the chemical reaction caused by direct electrical current.