Demonstration of Iodine


Chemicals needed

potassium iodide

sulphuric acid 96%  GSATZEND.gif (935 Byte) C    R 35   S (1/2)-26-30-45


Equipment necessary

test tube
lighter


Test procedure


Disposal

One can dispose of this small quantity of the diluted (caution!) reaction mixture into the drainage. Better it would be to beforehand reduce the iodine to iodide, e.g. through sodium sulphite.

Elucidation

In contrast to chloride iodide acts reductively on sulphuric acid. Therefore hardly any hydrogen iodide is formed, but mainly elementary iodine, as well as sulphur dioxide. The brownish colorings are most likely due to iodine which has been dissolved in water.

2H2SO4 + 2 KI  --> I2 + K2SO4 + 2H2O + SO2


Photos

Iodine vapors rise


Literature

to be added.