Electrolysis of water a small-scale electrolytic cell. It consists of three joined upright cylinders. The inner cylinder is open at the top to allow the addition of water and the electrolyte. A platinum electrode is placed at the bottom of each of the two side cylinders, connected to the positive and negative terminals of a source of electricity. When current is run through the Hofmann voltameter, gaseous oxygen forms at the anode (positive) and gaseous hydrogen at the cathode (negative). Each gas displaces water and collects at the top of the two outer tubes, where it can be drawn off with a stopcock.
Polarograph Polarograph A Polarograph is a chemical analysis instrument used to record automatic voltage-intensity curves. The Polarograph uses an electrolytic cell consisting of an electrode or microelectrode small area, generally of mercury drop type , which is a very fine capillary tube through which mercury flows slowly , which comes in the form of small droplets, which fall on the same surface of a much broader element, which is the other electrode . When one applies a variable voltage in this cell, the electrode large area remains unchanged, while the microelectrode undergoes a change of potential ,( i.e. is polarized). It