£1000 Prize; Hot Water v Cold Water: Freezing
Discussion
So, get your conveyor belts out and stick your 'planes on them for this one...
Why does hot water freeze faster than cold water?
http://www.rsc.org/AboutUs/News/PressReleases/2012...
Why does hot water freeze faster than cold water?
http://www.rsc.org/AboutUs/News/PressReleases/2012...
My theory is that warm or hot water mixes all the molecules together and breaks water down into smaller micro molecules and once it's popped in the freezer the cold affects the centre of the water quicker than if it was already cold, thus creating a crystaling/icing effect instantly at the core of the liquid.
Also I think cold water acts like people do in cold weather and hudle but in warm weather spread out which allows cold air to flow through the gaps quicker.
P'S
I know nothing.
Also I think cold water acts like people do in cold weather and hudle but in warm weather spread out which allows cold air to flow through the gaps quicker.
P'S
I know nothing.
Edited by PeanutHead on Wednesday 27th June 14:21
Edited by PeanutHead on Wednesday 27th June 14:22
all answers in science are made up! Cf Einstein, Higgs, Newton ..... K12beano said:
(You've said nothing about pressure - which is where my pet theory goes..... 
)
Indeed: )If you have 2 containers that are both sealed at atmospheric temp/pressure. Then raise the temp of one, then freeze both then....
However if you have 2 containers and heat one before sealing it then....
Convection currents. A hotter liquid will have a higher differential temperature across it, which sets up stronger circulating convection currents. This increases the rate of heat transfer across the surface. In other words, think of it as increasing the effective surface area of the hotter liquid. This circulation will continue even after the temperature has equalised with the initially cooler liquid.
Am I being thick? (no, please don't reply to that question)......but are they saying that water at 95degrees celcius will freeze quicker than water at 1degrees celcius if placed in to a freezer at say -5degrees celcuis?
ie. two cups of pure water at 1atm pressure.... one at 95 degrees and the other at 1 degrees...... both placed in to a freezer also at 1atm pressure which is at -5 degrees...... start the clock and watch as the 95 degrees cup freezes before the cup that was 1 degrees?
ie. two cups of pure water at 1atm pressure.... one at 95 degrees and the other at 1 degrees...... both placed in to a freezer also at 1atm pressure which is at -5 degrees...... start the clock and watch as the 95 degrees cup freezes before the cup that was 1 degrees?
Bedazzled said:
See here. Useful for making ice-cream, apparently.
In the same freezer at the same time? or seperate events? I have a recollection that a confounding factor is that if you put the hot water in the freezer, the freezer steps up it's chill capacity, hence shortening the freeze time. Wiki said:
If you take two similar containers with equal volumes of water, one at 35 °C (95 °F) and the other at 100 °C (212 °F), and put them into a freezer, the one that started at 100 °C (212 °F) freezes first.
Edited by Bedazzled on Thursday 28th June 13:44
Well here is an interesting graph...
http://olom.info/ib3/iB_html/uploads/post-1-47221-...
Can't vouch for its validity (or the surrounding environment conditions) but it is suggesting that a higher starting temperature liquid spends much LESS time in the transition between liquid and solid. By the look of it, about 1/3 of the time in this particular example.
So one thing that is easily apparent is that the higher starting temperature involves a higher rate of heat loss to the surrounding medium.
Another thing is that both starting temp liquids reach a value above zero whereby they go in to state transition. (ie. the formation of stronger molecular bonds that will define the chracteristics of it as being a solid).
What I can't explain is why the hotter starting temp would mean the transition stage only take about 1/3 of the time of that of the lower starting temp liquid.
(And I guess this is the crux of this topic).
http://olom.info/ib3/iB_html/uploads/post-1-47221-...
Can't vouch for its validity (or the surrounding environment conditions) but it is suggesting that a higher starting temperature liquid spends much LESS time in the transition between liquid and solid. By the look of it, about 1/3 of the time in this particular example.
So one thing that is easily apparent is that the higher starting temperature involves a higher rate of heat loss to the surrounding medium.
Another thing is that both starting temp liquids reach a value above zero whereby they go in to state transition. (ie. the formation of stronger molecular bonds that will define the chracteristics of it as being a solid).
What I can't explain is why the hotter starting temp would mean the transition stage only take about 1/3 of the time of that of the lower starting temp liquid.
(And I guess this is the crux of this topic).
llewop said:
... if you put the hot water in the freezer, the freezer steps up it's chill capacity, hence shortening the freeze time.
Don't think this has been mentioned:If the freezer is "frosty", a hot container will initially melt the frost below it and be in better contact with the cooling pipes. A cold container will sit on an insulating layer of frost.
Nimby said:
llewop said:
... if you put the hot water in the freezer, the freezer steps up it's chill capacity, hence shortening the freeze time.
Don't think this has been mentioned:If the freezer is "frosty", a hot container will initially melt the frost below it and be in better contact with the cooling pipes. A cold container will sit on an insulating layer of frost.
I was mildly curious as to whether the hot water is still evapourating at the top, meaning there is a) less water to freeze b) there's more water vapour in the atmosphere of the freezer (which will lose its energy much quicker) and like you've mentioned, form some sort of conductive atmosphere.
We (not me) should submit a PH based theory!
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