Question

which will freeze faster hot water or cold water and why?

Answer 1

Question: Which will freeze faster hot water or cold water and why?:

Answer: the phenomenon of hot water freezing faster than cold water is known as the Mpemba effect, named after Erasto Mpemba, a Tanzanian student who in 1963 was making ice cream as part of a school project.

"To the first part of the question--'Does hot water freeze faster than cold water?'--the answer is 'Not usually, but possibly under certain conditions.' It takes 540 calories to vaporize one gram of water, whereas it takes 100 calories to bring one gram of liquid water from 0 degrees Celsius to 100 degrees C. When water is hotter than 80 degrees C, the rate of cooling by rapid vaporization is very high because each evaporating gram draws at least 540 calories from the water left behind. This is a very large amount of heat compared with the one calorie per Celsius degree that is drawn from each gram of water that cools by regular thermal conduction.

Answer 2

$\underline \bold{Answer:-}$

If we will have an equal amount of hot and cold tap water and when we will place them in a freezer then the cold water will freeze faster.

This is first observed by a scientist named as Mpemba. On his name this effect is named as the Mpemba's effect. This is his observation defined below.

Mpemba's effect says that the warm water freezes more quickly than the cold water.

He has given his explanation as there is a better thermal contact between the refrigerator and the hot container than the thermal contact between the refrigerator and the cold container.

There are many more explanation given by the other scientist also but the above one is the most common.

The more explanation are as follows:-

1) In warm water the hydrogen bonding is beaker.

2) Evaporation take place in hot water and reduces it's mass so as it can cool faster.