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Suppose you have a container with a drain at the bottom full of frozen H2O which you leave a room temperature to melt. Will the ice melt faster if you drain the water as it melts?

I would expect that the water, being warmer than the ice, will speed the melting of the ice. However, I would also expect that draining the water would remove allow more air to enter the system and heat the ice faster. Which explanation is correct?

Related question: if the container is a cooler to fill with warm beverages, will the beverages cool faster in a wet or dry ice-filled cooler?

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1 Answer 1

Assuming the water and air are the same temperature (and that the air is mostly stationary) then the ice will melt quicker in the water. This is due to water having a higher thermal conductivity and heat capacity. In fact, this is easy to test: place a cocktail stick through an ice cube and lay it on top of a glass filled right to the top with (room temperature) water. The submerged half will melt quicker than that on top.

Regarding the second question: A warm object will cool quicker in icy water than in just ice for the same reason above but also because of increased surface area contact. However, icy water will be warmer than just ice. So the item will potentially be able to achieve a lower temperature in just ice (slow and steady wins the race).

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I think the main property at play is the thermal conductivity, rather than heat capacity. The faster the medium can conduct heat to the ice, the faster it will melt. –  buckminst Jul 29 '14 at 19:13
Assume that the water is colder than the air because it is recently-melted ice and no room-temperature water has been added to the ice. –  Slavatron Jul 29 '14 at 19:17
@buckminst You're right, both are relevant - I've corrected the answer. –  lemon Jul 29 '14 at 19:23
Actually, the water is the same temperature as the ice, at the melting point. Any heat transferred into the water gets transferred to the ice for it to melt. So any ice in the container will melt where the heat is applied. Your example of an ice cube on a cocktail stick is not correct since the water in the glass is not at the freezing/melting point. So the ice melts fast to cool the water down to the freezing/melting point. –  LDC3 Jul 30 '14 at 0:49

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