Experiment to show rate of diffusion in two gases
Answers
Explanation:
The results of the experiment:
-In the test tube, the two gases will diffuse towards each other. -When the two gases meet inside the test tube they react with one another and form a ring of Ammonium chloride that is white in color. - The ring is formed closer to the end where hydrogen chloride is
Explanation:
place concentrated ammonia solution on a pad in one end of a tube and concentrated hydrochloric acid on a pad at the other and watch as the two gases diffuse far enough to meet and form a ring of solid ammonium chloride
This demonstration is best performed in a fume cupboard. A black background, such as a sheet of black sugar paper, behind the demonstration helps the white ring to be seen more clearly. Actually performing the demonstration takes only a few minutes.
Equipment
Apparatus
Eye protection (goggles)
Access to a fume cupboard
Protective gloves (preferably nitrile)
A length of glass tube about half a metre long with an inside diameter of about 2 cm (note 1)
Retort stands with bosses and clamps x2
Small wads of cotton wool x2
Bungs x2 (to fit into the ends of the glass tube)
Strip of universal indicator paper (optional)
Chemicals
Concentrated hydrochloric acid (CORROSIVE), a few cm3 (note 2)
880 ammonia solution (CORROSIVE, DANGEROUS FOR THE ENVIRONMENT), a few cm3 (note 2)
Acetone (FLAMMABLE), a few cm3 (optional, note 1)
Equipment notes
It is very important that the tube is clean and completely dry for this experiment. If necessary, the tube can be dried by pushing a cotton wool pad soaked in acteone through the tube and leaving it for a few minutes.
The concentrated hydrochloric acid and the 880 ammonia solution are easier to handle in small bottles than in Winchesters (large bottles) for this demonstration.
Procedure
Working in the fume cupboard, clamp the glass tube at either end, ensuring that it is horizontal.
Open the bottle of ammonia solution cautiously, pointing the bottle away from both you and the audience. Open the bottle of hydrochloric acid and hold the stopper near the mouth of the ammonia bottle. Note the white clouds of ammonium chloride that form.
Put one of the cotton wool wads in the mouth of the ammonia bottle and carefully invert it to soak one side of it. Push the soaked end into one end of the glass tube. Replace the lid on the bottle.
Repeat this procedure quickly with a second wad of cotton wool and hydrochloric acid. Put the cotton wool wad into the other end of the glass tube.
Putting bungs into the ends of the glass tube will reduce the quantity of the gases which escape and therefore the smell. Once assembled, the tube can be removed from the fume cupboard.
Watch the tube and observe a ring of white powder forming near the middle of the tube. This is ammonium chloride