Under our definition of the Mpemba effect, akin to the definition in the ‘original’ paper by Mpemba & Osborne8 (in which they documented “the time for water to start freezing”) we are forced to conclude that the ‘Mpemba effect’ is not a genuine physical effect and is a scientific fallacy.

Particles move rapidly in all directions but collide with each other more frequently than in gases due to shorter distances between particles. With an increase in temperature, the particles move faster as they gain kinetic energy, resulting in increased collision rates and an increased rate of diffusion.

The molecules of cold water move slower than the molecules of hot water. The molecules of cold water move at the same speed as the molecules of hot water.

It’s important that the water be as close to boiling and the outside air be as cold as possible. The effect is less spectacular or won’t work if the water temperature drops below 200 degrees or if the air temperature climbs above -25 degrees.

Molecules in a liquid have enough energy to move around and pass each other. Molecules in a gas have lots of energy and spread out even more than molecules in a liquid. Warm water has more energy than cold water, which means that molecules in warm water move faster than molecules in cold water.

The evidence of the existence of particles in matter and their motion comes from the experiments on diffusion i.e. mixing of different substances on their own and Brownian motion. The zig-zag movement of the small particles suspended in a liquid or gas is called Brownian motion.

When water is heated, it evaporates. The molecules move and vibrate so quickly that they escape into the atmosphere as molecules of water vapor. Evaporation is a very important part of the water cycle.

212° F

Unless the humidity in the room is 100%, water in a cup absolutely will evaporate in a room with a constant temperature. It will evaporate if the temperature is 40 degrees blow zero (which, by the way is the point where the Fahrenheit and Celsius thermometers read the same). Frozen water will sublimate.

At room temperature, there is evaporation (I wouldn’t call it excitation). Even at low temperatures, there are some water molecules are have enough energy to escape and that’s why evaporation in water can occur at any temperature (yes, even if the water is in ice).

Water less than 0 can evaporate or sublimate. It depends on what is dissolved in it, or how pure it is. Pure water freezes at -48 C So liquid water can still evaporate well below 0 c. The trip state of water is 0.

Although it is true that acetic acid has a higher boiling point (about 118°C) in comparison with water (100°C), both will evaporate simultaneously. As you can see the vapor pressure of water is always higher in comparison with acetic acid. But the difference at room temperature at about 20°C is not that large.

Yes, cold water can evaporate. If the air is dry, you will see that even a cup of cold water will gradually evaporate away. If there’s enough moisture in the air, however, there may be more water molecules coming in from the air than there are leaving the water.

Most recent answer The boiling point of water is 100 deg C at 1 atm. And you are right that below this temperature (at 1 atm) water should not vaporize. Imagine a close system at 1 atm and 25 degree with a SINGLE water component, you will see that water never vaporize.

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