About Mpemba Effect:
- Mpemba effect is a paradoxical phenomenon in which a hot liquid can cool or freeze faster than a cold liquid under certain conditions.
- The effect was described by Aristotle, in his book Meterologica.
- It is named after Tanzanian student Erasto Mpemba, who brought attention to this counterintuitive phenomenon in 1969, makes for curious observation.
- Possible causes to Mpemba Effect:
- Micro bubbles: One cause, scientists have posited, is micro bubbles left suspended in water that has been heated by boiling.
- These cavities promote convection and transfer heat faster as the water cools.
- Evaporation: as warmer water evaporates more, it also takes away some heat (evaporation is inherently endothermic, which is how sweat cools your skin).
- Both convection and accelerated heat transfer are enhanced in warmer water because such water is less dense.
- Presence of frost in cold water: Frost is an insulator and could slow the loss of heat.
- Scientists have also considered whether compounds in water like calcium carbonate could be precipitated by boiling, and then dissolve, thus increasing the water’s freezing point.
Recent Findings related to Mpemba effect
- The researchers also found that the Mpemba effect is not unique to water.
- The simulation demonstrates that similar behaviour can occur during fluid-to-solid phase transitions in other materials.
- Supercomputer simulation of ice formation gives evidence of paradoxical phenomenon of water.
