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Water, at room temperature is poured into a hole made of a block of melting ice(kept at room temperature).I was wondering if the water will ever freeze?

Thank you.

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  • $\begingroup$ Assuming the block of ice is isothermal... no (neglecting statisitcal variability). $\endgroup$ – AdamRedwine Oct 24 '11 at 16:19
  • $\begingroup$ Can you please state the logic behind this? $\endgroup$ – Eisen Oct 24 '11 at 16:38
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    $\begingroup$ You have to give what temperature the ice is, i.e. if it is -18C and melting, how big the hole is,how big the block of ice is, what temperature the water is.Water poured into a small diameter deep hole in a -18C large block left at room temperature will freeze before it melts. $\endgroup$ – anna v Oct 24 '11 at 17:15
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Ice coming from the freezer will typically be around -19 deg. celsius, and can only be stored for a limited time at room temperature. As soon as the ice is heated to 0 deg. or above, the ice will melt into liquid water. Liquid water coming into contact with ice will be cooled, and if cooled below 0 deg. it will also freeze. The answer to your question is that it will depend on how much ice, how much water, and the starting temperatures of these(and much more if you really goes into small detail like the dynamic of energy transport). Everything is controlled by energy, to do the real calculations, you need constants like the heat capacity of water, and ice, and the melting energy.

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  • $\begingroup$ and the purity of the water as well... $\endgroup$ – AdamRedwine Oct 24 '11 at 17:46
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Water kept in the hole loses heat to the ice and cools down to 0°C. Here, both ice and water are at same temperature so that water cannot give out Latent heat to the ice and hence it does not freeze .

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Assuming the block of ice is at 0 degrees, the water will be kept at 0 degrees, and will evaporate at the top, and freeze at the bottom from the heat gone to evaporation until it is all solid ice.

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  • $\begingroup$ I can see how this could be right depending on the air conditions. Specifically, if the moisture content of the air was such that evaporation was allowed and the air temperature was also exactly 0 degrees. $\endgroup$ – Alan Rominger Oct 25 '11 at 21:02
  • $\begingroup$ The air temperature doesn't have to be zero- the thermal conductivity of the ice is much bigger. Evaporating to warmer air still cools you down. $\endgroup$ – Ron Maimon Oct 25 '11 at 21:13
  • $\begingroup$ Sure, so there's a moisture and temperature condition under which net cooling will occur, leading to what you describe. If the evaporation is not sufficient to compensate for heat gain, then the ice would just melt in a fairly ordinary fashion. $\endgroup$ – Alan Rominger Oct 25 '11 at 21:20
  • $\begingroup$ @Zassounotsukushi--- you are right. I believe this answer is the correct one under usual atmospheric conditions where the problem is useful, like water dropped into an ice-core drilled at the south pole in summer, where the air temperature is a little better than 0c, or water in an ice-cube at a cold temperature. The ice-cube melts, but the water evaporates, and leaves a little bit of ice at the bottom before the rest of the ice melts. $\endgroup$ – Ron Maimon Oct 25 '11 at 23:16
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Yes, if amount of ice is significantly larger than water; or else there's a large enough temperature difference between ice and water. this is entirely because temperature affects the mobility, kinetic energy and also extent of hydrogen bonding(which is significant in case of water as it accounts for density phenomenon at 4 degree Celsius). its been found that energy required to melt a unit amount of ice is significantly larger than energy required to raise its temperature by a unit degree. reason accounts for a higher latent energy than specific heat capacity of ice. since nature prefers least potential energy state(here; it prefers spending least possible energy in this process) in an ice-water system, equilibrium is achieved either by converting water into ice or vice-versa, or a mixture of both coexisting at zero degree. the origin of latent and specific heat capacities can be originated to packing, and types of molecular interactions involved in respective constituents.

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As water is poured into the hole, its temperature will decrease to 0 degree Celsius and it will be in thermal equilibrium with the ice. Finally it cannot loose any more heat energy after that and it won't melt.

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