Above: Heating mantle
There are several means of heating in the laboratory.
1. In the organic laboratories, the students used to use a hot plate with an aluminum block.
2. In research labs, oil baths, sand baths or heating mantles are commonly used. Oil baths works fine for most applications but cause an additional fire hazard when paraffin oil is used. Many paraffin oils start to smoke around 150 oC. Silicon oil is usually stable up to 250 oC.
3. In Chem 174, a heating mantle will probably be the best heating device to use. It consists of a metal wire (on the inside) that heats up when a current is applied. The other part (heat resistant cloth) protects this wire. There are several points to be consider when using a heating mantle:
a. The power input of the heating mantle has to be controlled. Never plug it directly into a wall plug. The heating mantle will burn out rapidly. It is imperative that it is plugged into a variac (power control).
b. The size of the heating mantle has to match the size of the flask. Heating mantles that are too big or too small do not provide a good heat transfer; the heating mantle will overheat and burn out quickly. In some cases, a better heat transfer can be accomplished by addition sand to the heating mantle that is slightly too large. However, the heating process is more difficult to control then due to lag time.