Because it takes more heat for the state change between solid and liquid.

Ice will absorb heat as it changes states between solid and liquid. Water at 0°C has more BTU's than ice at the same temp.

If you look at it molecularly, a solid is a very dense form of a material. The molecules are very close together. As more thermal energy is added the molecules separate and it becomes liquid. Water at 0°C is still a liquid and the molecules are closer together at that temp than they would be at 50°C but not nearly as close as the solid form of water (ice).

Hope this helps.

Drew

You said, "Water at 0°C is still a liquid and the molecules are closer together at that temp than they would be at 50°C but not nearly as close as the solid form of water (ice)."

Water at about 4ºC is more dense than ice. Else the Titanic would be rusting away in a Malaysian breaking yard.

Ok you are right, but why? Is it because the crystalization process increases the volume of a certain mole of water?

But...just because I was wrong about the density of water am I right about the state change absorbing more heat than just inserting the same quantity of water?

Drew

Yeah, you're right about the latent heat. The max density thingy is more complicated than I can usually even attempt to say. Here's somebody who is actually clear.

Start by clicking here

and then go here:

http://www.howeverythingworks.org/supplements/water_steam_and_ice.pdf

(In short there is a fair amount of energy required to change ice to water - the entire process occurs at a constant 0 deg C)

Good information on the How everything works website. Enhanced my understanding of the Joules required to change ice to water. It defines the statements I made above.

I know it is easier to just cut and paste a link to some good information, but there is something to be said for paraphrasing and laymans terms.

Drew

Perform a web search for "Phase change".

Because it take 80 calories to turn one gram of ice into one gram of water at 0 degrees C.

Concepts of latent heat and sensible heat are to be understood to explain this problem. Ice which is solid at o C gives up its latent heat till it becomes water at 0 C and hence when we put ice it adds cooling process.

Additional Latent heat of melting is required to melt the ice, which is not the case with cold water at same temperature hence ice cooling brings the temperature lower.

Kailash

Don't agree, water is thermally 25 time more conductive than air. Assuming a bottle is placed in ice there will be air pockets between the ice and bottle reducing the overall efficiency of the cooling process by lost surface area contact. I would place a little water with the ice to fill these gaps to promote greatest allowable cooling time and efficiency. Granted, if the ice could be formed to the exact shape of the bottle without an air-gap?? then the ice wins because same dencity water cannot be water and ice at 0 deg C at the same time

Spoken like a good beer-drinking fisherman! You are quite right from a practical point of view.

Thank you and yes, got my "practical" looking into a cooler box hoping the fish won't take a bite besides there's a time constraint, who wants interuptions when you have a potential thermal crisis?

Commonly called an "ice slurry".............and to keep large quantities of fish at the same temperature in the slurry the slurry must be stirred regularly, as water is such a poor conductor of heat.

Case in point.............when harvesting tuna from the farms they were finding that because of not agitating the slurry many fish were spoiling.......they were getting too "warm" in the slurry.........due to poor conduction..........regular stirring of the slurry overcame the problem.............and these fish were worth big money in the Japanese market.