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Quote: Originally posted by jawa on 26/5/2010

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Are the ice blocks better than a frozen water?

We tend to fill up a 2 litre water bottle and freeze that to put in the coolbox but wondered if Ice blocks are just just water in the or something different?

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Its all about the surface area to volume ratio. Ice block are usually thin so they will thaw quicker than any liquid you freez in a bigger 'block'. However think about how you are going to refreeze if you have to while you are away, most site freezers I have come across are pretty packed and smaller blocks might be easier to fit in than a couple of big bottles.

We have a huge cooler so I usually put a frozen 2 litre of water in each corner and cover the remaining floor of the box with thin blocks, we still have ice after 5-6 days in hot weather so it seems to work well. Keeping the box full also helps to hold the cold.

It depends on

• the latent heat required to turn solid into liquid - a gel will absorb more heat before it will turn liquid compared with water, therefore, it will keep the surrounding area cooler for longer.
• the surface area of the item to be melted - the smaller the surface area, the quicker it can absorb heat.

Therefore, like for like in size, an ice pack will keep the surrounding cooler than water.

I believe the above is true based on what I can remember from my chemistry lessons many years ago!

DK