Why does boiling water freeze when thrown in the air on a freezing day and cold doesn't?

Answer 1

The effect is known as the Mpemba effect. Believe it or not, but scientists have been studying this effect for a long time, since Aristotle, who was the first to note the phenominum is 300 b c, and are still not sure of the mechanisms envolved. There are 5 possible explanations.

1. evaporation. hot water evaporates faster than cold water and as it evaporates, it carries mass and heat with it, thus causing the temperature to drop faster.

2. disolved gasses. boiled water has less disolved gass wich there is speculation causes it to possibly loose heat faster, maybe because of greater convection

3. convection currents. hotter water may develop a different pattern of convection currents than cooler water causing it to loose heat faster. But if this is so, why as it approaches the temperature of the cooler water, does not the convection currents then emulate those of the cooler water.

4. surroundings. The hotter water may change the surronding environment in some way that effects its rate of cooling. As counter intuitive as this may seem, experiments have reported different results based on the size of the refrigeration unit used to conduct the experiments.

5. supercooling. Although water freezes at 32 F. It does not freeze at that temperature all of the time. Sometimes water can drop to a significantly lower temperature and remain a liquid. It might just be that water beginning at a higher temperature does not supercool as readily as water that begins at a lower temperature for some odd reason.

Answer 2

When you throw water into the air it will form droplets.
The size of the droplets will depend upon the surface tension.
Surface tension is dependent upon temperature. Surface tension falls as the temperature rises. The lower the surface tension, the smaller the droplet size.

Small droplets have a greater surface area per unit volume. A greater surface area per unit volume, allows for quicker cooling. Assuming near spherical droplets, the surface area of the droplet is proportional to r^2 and it's volume to r^3 where r is the radius. From this you can see that if the droplet radius is reduced the volume will fall much more than the surface area.

So, the hotter the water, the smaller the droplet size which gives a greater surface area per unit volume which makes cooling happen much quicker which means that it is more likely to freeze before hitting the ground.

Also note that because of air resistance, the smaller drops will fall slower and therefore have a greater chance of freezing before hitting the ground.

Answer 3

Does that really happen? Boiling water has a density closer to the density of ice, so the transition is energetically easier. Cold water needs to first shrink then expand a little again in order to solidify.

Answer 4

maybe the steam from the boiling water freezes, but the water iteself would be less likely to freeze than cold water because it has to lower its temperature by a greater amount..

Answer 5

That is because in hot water moleculas are more separated from each other and therefore they better mix with freezing air.

Answer 6

Because it's vaporizing and the small vapors freeze more easily than concentrated water.

Answer 7

i don't think boling water will freeze before cooling and getting colder

Answer 8

WHere did you get this information.

Question is based on wrong event.