Everyone has seen one. Those three bulbs stacked on top of each other with an outlet from the middle section and many of us, no doubt, saw one used in school to generate gases - even if gas cylinders are now favoured in laboratories. It was the last we ever saw of the Kipp which was reduced to smithereens - illustrating once more one of the problems we chemists face: invariably being associated with bangs, stinks and poisoning. I was immediately hooked.
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Figure 1. Figure 2. It is named after its inventor, the Dutch pharmacist Petrus Johannes Kipp — In any chemical laboratory where analysis is carried out, there needs to be a supply of hydrogen sulfide gas which can be turned on and off at will. Usually when a gas is made in the laboratory, the apparatus has to be set up each time the gas is needed.
Furthermore there is no way of switching the supply on and off. The same apparatus can also be used for supplying carbon dioxide or hydrogen on tap.
This is because to produce other gases heating is required. The gas flow is controlled by making gas only when a cold liquid is in contact with lumps of solid. Hydrogen sulfide, carbon dioxide, and hydrogen are all made in this way. When the liquid is drained away from the solid, the supply stops. No heating is needed to make them. They are made by the action of cold acids on pieces of solid. Broken sticks of ferrous sulfide are used for making hydrogen sulfide, marble chippings for carbon dioxide, and zinc granules for hydrogen.
Other sizes are also made. Basically it consists of three glass bulbs connected one above another. The solid needed to make the gas is placed in the central bulb by lifting off the top bulb and the glass tube fitted to it. A ground glass fitting connects this top section to the lower part.
A glass fitting stops the solid from falling down into the bottom bulb. The gas exit tube leaves from the central bulb. On it is a tap for regulating the supply of gas. The gas tap is opened and acid is poured in via the funnel at the top.
The uppermost section acts as a funnel to feed the lower section. There is no direct path from the top to the middle bulb. Sufficient acid is poured in to fill the bottom section and flood the solid in the center bulb. The gas tap is closed. Gas is produced and the pressure builds up inside the bulb, forcing the acid down into the bottom bulb and up into the top one.
When the liquid is forced out of the center bulb the generation of gas stops. The apparatus is now set up ready for use. When gas is needed, the tap is turned on.
The gas pressure in the center bulb is released. There is no extra pressure to hold the acid in the top bulb so it drops down to completely fill the bottom bulb and once more flood the solid. When the gas tap is turned off, as the gas can no longer escape, the pressure again builds up, forcing the liquid back into the top bulb or reservoir.
The build up of pressure ceases when all drops of acid left clinging to the solid have been used up. In time, the acid grows weaker and the solid is used up. The chemicals need renewing.
The acid is drained out by removing the bung from the lower bulb, after which the remaining solid can be taken out. This should be done in a fume cupboard to prevent the breathing of poisonous fumes. Related category Related video Encyclopedia index.
Classic Kit: Kipp's apparatus
The upper chamber extends downward as a tube that passes through the middle chamber into the lower chamber. There is no direct path between the middle and upper chambers, but the middle chamber is separated from the lower chamber by a retention plate, such as a conical piece of glass with small holes, which permits the passage of liquid and gas. The solid material e. The liquid, such as an acid, is poured into the top chamber. Although the acid is free to flow down through the tube into the bottom chamber, it is prevented from rising there by the pressure of the gas contained above it, which is able to leave the apparatus only by a stopcock near the top of the middle chamber. This stopcock may be opened, initially to permit the air to leave the apparatus, allowing the liquid in the bottom chamber to rise through the retention plate into the middle chamber and react with the solid material.
Plastic Kipps Apparatus