The formation of a sol

A small heap of powdered red iron oxide pigment

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Convert a rusty-brown precipitate of iron(III) hydroxide into a cherry-red iron(III) oxide sol in this demonstration. Includes kit list and safety instructions.

In this experiment, students observe as the teacher prepares and boils a small quantity of iron(III) chloride solution. As the solution is heated, hydrolysis produces hydrogen chloride and the solution becomes cloudier as iron(III) hydroxide forms as a precipitate.

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