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Ambitious_Jelly8783 t1_j3t2qfn wrote

Reply to comment by H4zardousMoose in Will water ice melt faster if allowed to drain, or remain in the meltwater? by terjeboe

If you keep the water, all things equal, the water will protect the ice. The melted water will keep at 0*C, protecting the ice, where the air will be warmer, so if no water the air will apply a higher temp to the surface.

Water requires a lot of energy to change degrees. It is actually not a great conductor. Now if you have warm water, same reasonkng applies as it has lots of energy so it'll melt it very quickly.

Someone do the experiment and share it.

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raptir1 t1_j3tugsn wrote

> Water requires a lot of energy to change degrees.

Not compared to the amount of energy it takes to melt ice. Melting ice takes nearly 80 times as much energy as it takes to warm water 1C.

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ubik2 t1_j3t7k8m wrote

At some point, the extra surface area of the water/air interface means more heat is transferred from the ice cube to the air. If the surface area is small, the more important factor is that it slows the transfer from the ice.

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H4zardousMoose t1_j3xyimx wrote

I think you are conflating thermal conductivity (how well thermal energy propagates through a material, measured in W/kg*K) and thermal capacity (how much energy a given amount of a material can hold, usually measured in J/kg*K).

Water has high values in both btw. So it takes a lot of energy to heat up and cool down, but it also exchanges energy quickly within itself and to it's surroundings.

Now instinctively I thought that water would have a higher thermal conductivity than ice, because Iglus insulate so well. But snow isn't ice (crazy I know:D) and it turns out ice has about a 4 times higher thermal conductivity than water at 0°C.

Therefore: If you cover the ice in a thin layer of water, this should slow down the melting. But if you put the ice into a decent sized container with water, where the total surface area of the mixture becomes more than 4x larger than the surface area of the ice it should speed up the melting process. This effect should also increase the further along the melting process you are, since the surface area of the ice will decrease (less of it left), where as the surface area of the mixture remains mostly equal (ice has a bit less density I know, but small effect).

So I learnt something: Solids generally conduct heat better than liquids. But the original point, where it depends on the container and it's conductive surface area still mostly remains valid.

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