Remember 10 atmospheric pressure 40L steel cylinder, which is about 300 cubic meters. The price is 48 yuan per bottle, which is made of oil, natural gas and coal. The price is low, but the purity is not high; If you buy a bottle of electrolyzed water, it's about 160 yuan, which is expensive but high in purity, 99.999%.

The prices of liquid helium, high-purity helium and pure helium and industrial helium are as follows: liquid helium 150/ liter, high-purity helium 680/ bottle, pure helium 580/ bottle and industrial helium 450/ bottle.

Where to buy: Helium is generally bought by wedding companies or ordered directly from chemical plants; Hydrogen may have to be ordered at special chemical plants. Sometimes you buy too little and people don't buy it yet!

When I need hydrogen, I usually make it myself. The principle is simple. Every city has a chemical market. I went to the chemical market to buy a bottle of sodium hydroxide (500g), which is about 10 to 15 yuan, and then I made a solution. Then I put the aluminum sheet on the fire, cool it and put it directly into the solution, which will produce hydrogen. Because it is burnt, there will be no obvious phenomenon at first.