Does hot water freeze faster than cold water and why?

Anonymous 12/31/2017. 8 answers
Science & Mathematics Chemistry

8 Answers

Nags 01/01/2018.

Hot water tops cold water because cold is denser than hot volumes (exception to anamalous temperatures). When the hot layer on top gets in contact with VERY cold air, it solidifies so fast that it gets locked to neighbor crystals before drowning into layers below. Thus in certain conditions, hot water freezes faster.

az_lender 12/31/2017.

This is a very old controversy. Google "Mpemba effect" to learn more than you probably want to know. Science remains open to the possibility that hot water DOES freeze faster than cold water under certain circumstances, but there is no scientific consensus about an explanation, and some scientists believe there is no such effect at all. Peer-reviewed journals have carried BOTH opposite findings in recent years.

D g 12/31/2017.

its an unscientific idea .. the mhembla effect spelling may be incorrect.. a person noticed that hot water seemed to freeze faster..

it is unproven because it cant be reproduced it may happen or it may not when tested it depends on what you define as FROZEN..

TO FREEZE solid the water has to LOOSE the heat it has plus some energy at freezing..

the energy it needs to lose at freezing is constant..

the idea probably comes from the thought that difference in temperature increases the temperature loss

a scientific analysis though can show that

a) even if the starting temperature of the water say is 100 degs C for one amount

and 50 deg C for another sample..

the sample that is currently 100 degs .. must eventually become the temperature of 50 degs..

at which point it will take the same time to lose heat as the original 50 degs sample..

so the 100 deg sample must take the the time it needs to lose heat to 50 DEGS PLUS the time it takes to lose heat from 50 TO 0..

Mark big sky boat man 12/31/2017.

No, it doesn't, because freezing happens when the temperature gets to 0(or thereabouts) so if the water starts off hotter, it takes longer to freeze.

edkootz1 12/31/2017.

No, it doesn't. It freezes at a faster rate, but if you freeze water that starts at 180 degrees vs. water that starts at 80 degrees, the 80 degree water will freeze first. I used to drive a Zamboni, and people always think the Zamboni uses hot water so that it will freeze in time for the next hockey period, or skating session. That's not true. A Zamboni uses hot water so that it will melt the cracks, and then when it freezes, the ice will be smoother.

Anonymous 12/31/2017.

Yes, once i when outside in the freezing cold with hot chocolate it frozed in five secs. Sad day. I become very depressed after that

Gillian 12/31/2017.

no cause cold water is already cold so to freeze it doesn't have to drop its temperature as much to get to a freezing point. Hot water has to drop lower to hit the freezing point so it takes longer

rob 12/31/2017.

Nope obviously kid