Although the effect seems impossible at first glance, it has been seen in numerous experiments, was reported by Aristotle, Francis Bacon and Descartes and is well known as folklore throughout the world . It has a rich and fascinating history, culminating in the dramatic story of secondary school student, Erasto Mpemba, who reintroduced the effect to the 20th century scientific community. The phenomenon, although simple to describe, is deceptively complex and illustrates several important questions about the scientific method: the role of skepticism in scientific research, the influence of theory on experiment and observation, the need for precision in stating a scientific hypothesis and the nature of falsifiability. We examine the theoretical mechanisms proposed for the Mpemba effect and the results of modern experiments on the phenomenon. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay. Studies are also described on the observation that hot water pipes are more likely to burst than cold water pipes. First I will tell the story of a surprising experiment. The experiment is based on an observation made on several occasions that seems to go against common sense. The observation is that if approximately equal quantities of a hot and a cold liquid are placed together in a freezer, then the hot liquid freezes first. This seems to me to be a great example of what science educators call a discrepant event (cognitive dissonance/cognitive conflict). A discrepant event is an event that is contrary to our current beliefs. Discrepant events are said to be useful in allowing students to reconstruct concepts that have been imperfectly understood. The literature on discrepant events is relatively small and the following are the main easily accessible references (Fensham & Kass, 1988; Hand, 1988; Thompson, 1989). One of the many unsolved mysteries of science, it will remain a mystery for me to be able to achieve satisfactory results. and logical results, the physics teacher advised me to repeat the experiments to demonstrate the results and to make sure they are real. So basically what I'm trying to do is explain the Mpemba theory and find out if it's true that hot water freezes faster than cold water? I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is due to the lowering of the freezing point by solutes, both gaseous and solid, whose solubility decreases with increasing temperature in so that they are removed when the water is heated. Solutes are concentrated ahead of the freezing front by zone refining in unheated water, reducing the temperature of the freezing front and thus reducing the temperature gradient and heat flux, slowing the advance of the freezing front. Method: Apparatus used: • Small freezer with internal temperature: to freeze water from -19.1° to -18.8°C • Cylindrical aluminum calorimetric containers 65 mm high by 48 mm in diameter • Electric kettle: to boil water• Deionized water: water free of charged atoms or molecules, used primarily in the production of water-based cleaning chemicals.• Digital data logger: to record data over time.• Temperature probes : to measure the initial temperature.• Paper towels:• Cling film: to cover frozen water • Duct tape: to cover the area where unwanted substances are not needed • Mains power: to power the small freezer and the electric kettle. To obtain variable initial temperatures,Cold deionized water was prepared at different depths in six aluminum vessels (bare and open; bare and sealed on top with cling film; insulated and open; or a combination of these). Boiled water from a kettle was used to top up so that the total volume of water in each vessel was 100 ml. The digital temperature probes were secured with adhesive tape so that the head of each probe, 8 mm long, was completely immersed in the surface of the water and these were connected to a data logger which sampled the temperature of each probe at 10 intervals. Each container was placed on an insulating layer of folded paper towel to minimize conductive heat loss through the layer of frost on the freezer shelf. A schematic of the experimental setup is presented in Figure 1. Numerous mechanisms have been hypothesized to explain the Mpemba effect. Monwhea Jeng [2] and Marek Balazovic and Boris Tomazik [3] have written an excellent overview on the topic summarizing these hypotheses. One is that the initially warmer vessel melts the layer of frost on which it sits more completely than the colder vessel; when this refreezes it creates a better thermal contact which removes the heat more quickly. Placing the container on insulating layers of folded paper towels immediately eliminates the possibility of this hypothesis being effective. Boiling the water first also reduces the presence of dissolved gases, which had also been claimed to contribute to the effect. Supercoiling, when a liquid remains fluid below its freezing point before spontaneously becoming solid, has also been proposed as an explanation. James D Brownridge states: "Hot water freezes before colder water only when the colder water overcomes supercoiling, and then, only if the nucleation temperature of the colder water is several degrees lower than that of the 'hot water. The water to be heated can lower, rise or not change the spontaneous freezing temperature.' [4]Although this may be the case in some circumstances, it is not a satisfactory explanation for the following reasons. First, supercoiling is capricious. Temperature graph for two isolated vessels; the water in the vessel represented by the blue line starts only 4.45°C warmer than the red line but starts freezing 15.5% faster. Graph of time to onset of freezing versus initial temperature. Red corners: bare vessels, covered by film transparent. Blue squares: isolated, open vessels; this graph is similar to that presented in Mpembaand Osborne's 1969 paper. The phenomenon was not observed to occur at temperatures below about -1°C, if it occurred. Impurities in the water, surface imperfections on the inner faces of the vessel, and even the very presence of the temperature probe head consistently tended to cause nucleation and freezing at or very close to 0°C. Efforts were made to encourage supercoiling (using deionized water and in some experiments immersing only the tip of the temperature probe), but supercoiling was still difficult to achieve. Second, Mpemba first observed the effect in ice cream, which is very unlikely to cool too much; ideally we would like a general explanation that also explains Mpemba's original observations. Third, the Mpemba effect has been observed several times without supercoiling, as shown in Figure 2. Evaporation and convection have also been proposed separately (by Mpemba in his original paper and by Jeng, Balazovic, and Tomazik). This investigation finds evidence to suggest that the effect is caused by.