Dry ice call solid carbonic acid. Main distinctive feature the fact that it is capable to turn instantly into gas is its, passing liquid aggregate state. Dry carbonic acid is applied, for example, in portable refrigerators — those in which sell ice cream. Receiving dry ice takes place in industrial conditions in three stages.
It is required to you
- - baking soda;
- - laboratory glassware;
- - siphon with barrels;
- - fire extinguisher;
- - goggles;
- - gloves;
- - dense package.
Instruction
1. A small amount of dry ice can be received by means of several chemical experiments. Receive carbon dioxide. Take crystal soda. It is possible to use usual drinking. Fill it in a flask. Pour in solution of the divorced hydrochloric or acetic acid there. Close a flask a rubber stopper with a tube. Take away a tube in water. Collect the rising bubbles in a test tube. It is also carbon dioxide. In industrial conditions for receiving carbon dioxide, monoethanol amine is most often applied now.
2. Liquid carbonic acid is a solution of carbon dioxide in water. It is known to much as sparkling water without syrup. This connection is extremely unstable. At room to temperature liquid carbonic acid intensively decays on water and carbon dioxide which comes out in the form of bubbles. It is possible to observe it, having taken a usual household siphon and having charged in it the gas spray. Filling from it a glass of sparkling water, you will be able to observe carbonic acid decomposition. For industrial production of dry ice liquid carbonic acid is transported in special tanks where it is under big pressure.
3. For receiving dry ice the liquid carbonic acid which is under pressure is used. In the conditions of school laboratory it is impossible to receive such pressure therefore take already ready substance. There is it, for example, in the carbon dioxide OU fire extinguisher. Put on goggles and dense gloves. Remove a seal and take out safety to the check. Take a dense bag and put on it a fire extinguisher bell. Press the lever and release a little being under pressure of carbonic acid. It has to get to a bag.
4. Release the handle. Remove and turn out a bag. In it you will see a number of the dry white substance similar to ice. It is also dry ice. The compressed carbonic acid at expansion absorbs a lot of heat. At the same time she is sharply cooled. In industrial conditions produce the granulated dry ice or packaged in the form of blocks. For this purpose there are special installations — pelletayzer and block makers.
5. By industrial production of dry ice a part of carbonic acid turns into gas again. Other passes into a firm state. It is forcibly condensed and cooled. At first quite friable substance which call still "dry snow" is formed. It represents some kind of semi-finished product. It is driven into installation and pressed therefore dry ice turns out.