Originally Posted by
cyccommute
Bingo! Generally speaking, heating up chemical reactions doesn't slow them down or eliminate them. It speeds them up...most times significantly. A rule of thumb we use in chemistry is that a 10°C (about 20°F) rise in temperature doubles the reaction rate. Heating the chain and water to 212°F from 70°F is a 14 fold increase in reaction rate. Basically, the water evaporates more quickly but it rusts much more quickly as well.
Thermodynamic note: You only have to worry about the temperature to the boiling point of water. Once the water is gone, the vehicle for easy oxidation of the iron is mostly gone as well.
It doesn't matter if the reaction is faster, the point of heating the chain is to get rid of the water. 10g of water left on the chain will cause significant rust overnight. Heat it up and all the water will be gone in 10min. Even though the reaction may be faster for 10min it's unlikely you'll notice any rust because most of the water will not be contributing to the reaction.