According to the British journal New Scientist, sometimes, hot water freezes much faster than cold water. This bizarre phenomenon has puzzled scientists for years.
Explaining Why Hot Water Freezes Faster than Cold Water
After hundreds of experiments, scientist James Bulangliqi from the State University of New York has finally proven this phenomenon.
According to James Bulangliqi, the phenomenon is related to certain impurities present in the water.
The phenomenon of hot water freezing quickly is known as the “Mpemba effect,” named after high school student Erasto Mpemba from Tanzania.
Physicists have proposed various hypotheses regarding the Mpemba effect. However, the differing explanations have failed to convince everyone, as this effect is unreliable; cold water consistently freezes faster than hot water.
Scientist James Bulangliqi believes that the impurities in the water are the key factor leading to the rapid freezing of hot water.
Over a span of 10 years, James Bulangliqi conducted hundreds of experiments related to the Mpemba effect. Eventually, he discovered evidence that the Mpemba effect stems from an unstable supercooling phenomenon.
James Bulangliqi stated: “It seems that water does not freeze at 0 degrees Celsius; rather, it typically freezes at lower temperatures, which is the supercooling phenomenon. The freezing point is influenced by impurities that establish the relationship between water and ice. Under normal circumstances, water can contain various types of impurities, including dust, dissolved salts, and bacteria. Each impurity can affect the freezing mechanism at specific temperatures.”
James Bulangliqi experimented with two samples of tap water at the same temperature of 20 degrees Celsius.
First, he placed the water samples into test tubes, then put them in a freezer to freeze. The random mixture of impurities resulted in the two water samples having different freezing points, with one sample having a higher freezing point. If this difference is significant enough, the Mpemba effect will manifest.
James Bulangliqi selected the water sample with the naturally higher freezing point and heated it to 80 degrees Celsius, while the other sample was kept at room temperature, before placing both test tubes back into the freezer.
James Bulangliqi noted that if the freezing point of hot water is at least 5 degrees Celsius higher, its freezing speed will be significantly faster than that of cold water.
As we know, each water molecule consists of one oxygen atom covalently bonded to two hydrogen atoms. Individual water molecules also bond with each other through hydrogen bonds, which are created when a hydrogen atom is near an oxygen atom of another water molecule.
The hydrogen bonds pull water molecules closer together, initiating a natural repulsive force between them, causing the covalent bonds between oxygen and hydrogen to stretch and store energy. When water is heated, the atoms move further apart, causing the bonds to stretch.
The bonding force causes water molecules to contract back and release energy, leading to cooling, which means that hot water freezes faster than cold water, thus explaining the Mpemba effect.
However, some physics experts note that the above explanation cannot currently be used to predict new properties of water that may arise from shortening the covalent bonds. Therefore, there is still one step left to resolve before the mystery is satisfactorily explained.
