Page 41 - Curriculum Visions Dynamic Book

Chlorine displaces iodine
The halogens form a family of elements with similar properties and that form similar compounds. When put together, the more reactive will displace those that
are less reactive as shown to the left and below. When chlorine
is bubbled through colourless potassium iodide solution, it turns brown. This colour is caused by tiny solid crystals of iodine that will, over time, settle out on the bottom of the beaker, leaving a clear solution of potassium chloride.
➡
condensation nuclei: microscopic particles of dust, salt and other materials suspended in the air, which attract water molecules.
vapour: the gaseous form
of a substance that is normally a liquid. For example, water vapour is the gaseous form
of liquid water.
 Chlorine gas is produced and bubbled through a beaker filled with a solution of potassium iodide. The brown colour is the iodine displaced by the chlorine and released into the solution.
Iodine and health
Iodine has long been used
as a mild antiseptic and disinfectant. You will also find iodine combined with some detergents that claim to disinfect as well as clean.
EQUATION: Displacement of iodine by chlorine
Potassium iodide + chlorine gas ➪ potassium chloride + iodine 2KI(aq) + Cl2(g) ➪ 2KCl(aq) + I2(s)
Also...
Fluorine is the most reactive
of the halogens, followed by chlorine, bromine and then iodine as we descend the group in the Periodic Table (see page 47).
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