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Chemistry Gases Testing

Testing for Gases

  1. The first test I performed was the hydrogen pop test. I added Mg ribbon to dilute HCl in a test tube. Once the acid is in, hold your thumb over the top of the tube until some pressure is felt. Then over a flame or by inserting a glowing splint into the tube a pop will be heard. This is Hydrogen reacting with the flame (O2) to give water.
  1. Next was the oxygen test. I added two spatula loads of solid potassium permanganate to a boiling tube and proceeded to heat the tube thoroughly. When enough time has elapsed light a glowing splint and insert it halfway down the tube. The glowing splint should relight instantly giving it a bright flame.
  1. The test for chlorine is pretty simple. I held some filter paper saturated in potassium iodide over the chlorine gas and it changed from colourless to brown. I used some liquid chorine but I am not sure of how to produce chlorine in a reaction, but I am sure Rudi will be able to tell us.
  1. Hydrogen Sulfide gas was produced by reacting iron sulfide with hydrochloric acid. Then I used some filter paper saturated in lead acetate and held it over the top of the test tube I used. There was an observed colour change on the paper that confirms the presence of hydrogen sulfide. Another test for hydrogen sulfide is by smell. But be careful, once you can not smell the gas it is toxic.
  1. To test for sulfur dioxide I used some sulfurous acid which gives off sulfur dioxide in the gas phase. I then got some potassium dichromate and held it over the top of the bottle of acid. A colour change is observed.