Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
-----------------
hydrochloric acid : HCl
sodium chlorite : NaClO2
sodium bromate : NaBrO3
Class:
------
elem=Cl,Br
redox
Summary:
--------
When concentrated hydrochloric acid is added to solid NaClO2, then a lot of
intense yellow ClO2 is produced, but normally the gas does not explode.
When concentrated hydrochloric acid is added to a mix of solid NaClO2 and solid
NaBrO3, then a yellow gas is produced and within a few seconds at most, the gas
explodes, the explosion starting at/near the liquid surface.
Description:
------------
Take a small amount of solid sodium chlorite (80% commercial grade is
suitable), put this in a thick-walled test tube and add 2 ml or so of 35% HCl:
When this is done, a lot of intense yellow chlorine dioxide is produced. The
gas bubbles from the liquid vigorously. The test tube quickly is filled with
nearly pure ClO2.
Leave the test tube standing for a while: Slowly, more ClO2 is released from
the liquid and the gas also slowly diffuses from the test tube. It can be
ignited with a flame, which results in a loud WHOOSH sound.
---------------------------------------------------------
Take a small amount of solid sodium bromate and mix this with a similar amount
of solid sodium chlorite. Put this mix in a thick-walled test tube. Only take a
very small amount (e.g. 50 mg of each chemical, not more!). Add 2 ml or so of
35% HCl: As soon as the HCl reaches the solid mix, a lot of gas is produced.
This gas has a strong golden yellow color. Suddenly (usually within a few
seconds) the gas above the liquid explodes with quite a loud bang. The
explosion starts just above the liquid surface. Afte
---------------------------------------------------------
The experiment with NaBrO3 and NaClO2 was repeated two times and both times
lead to an explosion. The experiment with only NaClO2 was repeated many times,
even a few times in full sunlight, and no explosion occurred in one of these
experiments.