What type of chemical reaction will occur when iron (III) hydroxide is heated and forms new products?

Decomposition

Explanation:

A decomposition reaction is a type of reaction in which a compound is broken down into its constituent elements sometimes under the influence of heat.

When  iron (III) hydroxide is heated,new products are formed according to the equation; 2Fe(OH)3 > Fe2O3 + 3H2O.

This is a thermal decomposition reaction.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.