Boiling chip

 ( Laboratory Equipment ) 

A boiling chip, boiling stone, or porous bit anti-bumping granule is a tiny, unevenly shaped piece of substance added to liquids to make them boiling more calmly. Boiling chips are frequently employed in distillation and heating. When a liquid becomes superheating, a speck of dust or a stirring rod can cause violent flash boiling. Boiling chips provide nucleation sites so the liquid boils smoothly without becoming superheating or bumping.

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Use Boiling chips should not be added to liquid that is already near its boiling point, as this could also induce flash boiling. Boiling chips should not be used when cooking unless they are suitable for food-grade applications.

The structure of a boiling chip traps liquid while in use, meaning that they cannot be re-used in laboratory setups. They also don't work well under vacuum; if a solution is boiling under vacuum, it is best to constantly stir it instead.

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Materials Boiling chips are typically made of a porous material, such as alumina, silicon carbide, calcium carbonate, calcium sulfate, porcelain or carbon, and often have a nonreactive coating of PTFE. This ensures that the boiling chips will provide effective nucleation sites, yet are chemically inert. In less demanding situations, like school laboratories, pieces of broken or glassware are often used. (dead link 2018-08-07)

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