you need
  • sulfuric acid, sodium nitrate, flasks, burners.
Pour into a glass flask, 90 grams of sodium nitrite (sodium nitrate).Pour to the same 100 grams of concentrated sulfuric acid (you can take and dilute acid , but stronger than sulfuric acid, nitric acid is the stronger) and a little shake.
Next, close the flask with a lid and heat the mixture in a water bath, keep the temperature around 80 degrees.In the process, in a closed flask will appear gas - is nitrogen dioxide.When sodium nitrate is completely dissolved in sulfuric acid, turn off heat, let the liquid cool down.
After cooling, the flask is nitric acid with a mixture of sodium sulfate, these substances should be divided.Remove the bulb cover normal wear and cover it with a gas outlet tube.The second end of the tube was placed in another flask with cap, which put in cold water.The cover of the second bulb, for safety, insert another tube and attach to it an ordinary balloon.
Put the flask with a mixture of the burner and heat the mixture to a boil.From the first flask acid will evaporate, leaving a residue of sodium sulphate, and the second flask to condense.After the end of the process, let the acid cool, pour it into a glass container and close the lid.