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Please help me with an answer to my dilemma:

Is there a liquid that could be used to fill an ice rink (non-explosive, non-poisonous, etc), and have the freezing point above 0 Celsius?

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Iron- it has a freezing point well above zero degrees. Seriously though, water is used because it is plentiful, freezing point is at a useful temperature, plumbing is already understood and simple at this temperature and it is largely safe. – Rory Alsop Dec 15 '12 at 13:37
Thank you for your comment,if such a liquid exist will help me spare a lot of electricity used to freeze the water. – Muresan Dec 16 '12 at 5:27

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The answer to this question is "probably not". The reason for this is quite interesting.

Ice skates have such low friction because a layer of water forms in between the ice and the blades. In order for this to happen, you need a substance that will turn from solid to liquid when it's compressed, which (according to thermodynamics) is the same thing as having a liquid that expands when it freezes. If you don't use a substance with this property then your skates are just resting on a solid surface and friction will prevent you from going anywhere.

But water is quite unusual in having this property. There are other substances that do it, but not many. The most comprehensive list I can find includes only water, silicon, gallium, antimony, bismuth and acetic acid. The metals can all be ruled out because you'd have to heat the floor up to close to their melting point. Acetic acid comes close: its melting point is $16$-$17^\circ C$, so you could in principle skate on a floor made of the stuff at only a little below room temperature. But unfortunately pure acetic acid is corrosive and has a pungent smell (it's what you can smell in vinegar, but this would be the purified version, so much more intense) so it wouldn't be suitable for a public place.

Maybe there is another molecule that has the desirable properties, but it seems kind of unlikely, because these substances are easy to spot - the solid phase floats on top of the liquid one - so if there was another one it would probably already be known.

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Thak you very much Nathaniel, perhaps a solutions, a mix of more than one liquid will have such freezing point.For me it's important to find such a liquid or mixture to spare the electricity used to freeze the ice rink. – Muresan Dec 16 '12 at 5:30
@Muresan the problem is that all the known substances with the expanding-on-freezing property are metals, apart from acetic acid. The list I linked to says some of bismuth's alloys also expand, so maybe you could lower its freezing point by mixing it with mercury, while still keeping the expansion property (this seems unlikely to me but I don't know enough chemistry to say for sure) - but mercury releases toxic vapour, so it wouldn't be suitable for a public place. – Nathaniel Dec 16 '12 at 9:00
@Nathaniel: "you need a substance that will turn from solid to liquid when it's compressed, which (according to thermodynamics) is the same thing as having a liquid that expands when it freezes" could you point me toward some reading material on that ? – josinalvo Dec 16 '12 at 15:26
@josinalvo I first learned about the layer of water in this video of Richard Feynman talking about magnets, which is worth watching. The equivalence between melting on compression and expanding on freezing is because it's a reversible transition, so the volume change has to be the same in each case - if that's the bit you want to learn more about then you'll need a good introductory textbook on chemical thermodynamics or physical chemistry, but I don't have a specific one to recommend. – Nathaniel Dec 17 '12 at 1:56

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