How can we make a perfect pneumatic cylinder?

Camphor (synthetic), anhydrous ethanol (99.7% alcohol), ammonium chloride and chemical purity (CP) of potassium chloride can be used.

Appliances: glass bottle (360ml), beaker, measuring cylinder, glass rod, medicine spoon, gloves, mask (camphor and alcohol smell heavy), electronic scale (accuracy 0. 1g).

Proportion: potassium chloride? 2.5g, ammonium chloride 2.5g, camphor 10g, alcohol 40ml, distilled water 33ml, close to 80ml. Formula potassium nitrate, but in fact potassium nitrate is controlled because it is easy to manufacture and easy to explode. Unless the teachers and students at school can apply, the average person can't buy it. So will potassium chloride.

The principle of gas cylinder is that when camphor, potassium chloride and ammonium chloride are mixed, when the temperature changes, the solute in the system will precipitate due to the change of solubility. Due to the different precipitation speed and quality, small snowflake-like and feather-like crystals will be formed at different temperatures. Camphor mainly precipitates.

Operation method:

Dissolve potassium chloride and ammonium chloride in warm water, directly dissolve camphor in alcohol, and then mix. Camphor is relatively soluble in alcohol, but rarely in water. Therefore, if cold water is used directly, it is basically turbid after mixing, which is inconvenient to transfer to glass bottles. It is best to heat in a water bath.

It doesn't matter if the amount of camphor is reduced properly. In addition, if the concentration of alcohol used is relatively low, the actual ratio of water to alcohol will change, which is likely to affect the amount of crystallization. You have to adjust yourself.

Finally, in the crystallization process, don't cool too fast. Natural cooling is the best. When cooling crystallization, it is best not to put it directly on the cold desktop, but to put a book on it. Open containers are easy to float and crystallize because the liquid level drops rapidly.