A piece of cotton wool soaked in Ammonia solution is placed at one end of a glass tube and at the same time another piece of cotton wool soaked in concentrated Hydrochloric acid is placed at the other end . A white ring of Ammonium chloride forms at a point alone the tube after a few seconds . If the two pieces of cotton wool are one metre apart, calculate the distance between the cotton wool soaked in Hydrochloric acid and the white ring .
Answers
Answer:
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.