Ok, I know this doesnt help with anything but I thought you guys might know this. I started school again today and am taking a chem class. The professor said water will freeze at 0 degres celcius and like wise it will melt at 0 degrees celcius. Can someone explain to me how if I put water in a freezer that has a temp of 0 degree celcius, why it would melt at the same temp? It doesnt make sense to me...

If you have an ice cube and you brought it up to 0C some of it would melt and there would be some water. It would not melt completely, but there would be water present.

Likewise if you have a jar of water and brought the temp down to 0C there would form some ice crystals. It would not freeze solid, but there would be ice present.

Not sure if that helped. A chemist might be able to explain it a lot better.

But if that ice cub started melting, what would stop it from melting? The temperature already shows its warm enough to melt. Same with the freezing of the water.... If the temperature maintained 0C, what would stop the transformation in progress?

Thanks for the reply

Freezing and melting temperature is practically the same. Iron melts at 1538 C which is the temperature it starts becoming liquid (melting). But if you take liquid iron that is 2000 C and cool it to 1538 and below it will start
"freezing" or becoming solid.

Same with water. Water becomes ice at 0 and below and becomes liquid from 0 and above. What the professor was trying to explain is that 0 is basically the turning point. At 0 degrees the water balances from becoming a more solid ice or a more liquid water.

Hope that helps!

so at exactly 0 degrees it would be half water half ice?

would it have to be 0.06C to melt ice and .05C to freeze it? Im not understand why the ice cube that I just froze wouldnt melt based on what she is saying. Their has to be a measurable difference within the degree for the melting and freezing point, no?

To explain this, let's start the other way around; what does freezing water mean? Or, what actually happens to the water (or any other liquid substance) when it becomes solid?

Is this a rhetorical question? Transforming a liquid to a solid.... which the heat from the water would be melting the newly formed ice on the surface?

If I put an ice cube from one 0C freezer to another, its not going to melt right? But if I put water in the either freezer it would freeze. I know im missing something. But the whole ice to water thing is really throwing me....

of course, it's pressure-dependent as well.

you guys are making this harder hahah

but then at some specific pressure, at 0 degrees, will it be half water half ice (and anything slightly lower will freeze everything and any more energy will make it all melt eventually) ?

No, it's not rhetorical, hahaha

I was just asking about what is happening to the molecules of the water when it freezes. Basically they can form a solid crystal. Now, the 0 C temperature is the conditions for the crystal to form (this is in physiological pressure, thanks benzyme for bringing it up!). Below 0 crystals will continue forming to a solid piece of ice.

At exactly 0 degrees there's going to be an equilibrium between ice crystals forming and ice crystals melting. It does not mean that it is going to be 50% ice and 50% water but it's going to be "something like that". Endlessness is very close to correct.

0 degrees is not exactly the freezing point or melting point of water or ice. It is the point where ice crystals begin to form and as well the point at which ice crystals begin to decompose. As I said, it is an equilibrium; this means that the rate of crystal formation is equal to the rate of crystal decomposition. If you kick the temperature just below 0, say -0.001 C the water will crystallise faster than it melts so eventually it will freeze but it'll take time. If you go to -10 C then the water will form crystals much faster and the crystal decomposition rate is going to almost non-existent.

The opposite will be true for thawing jsut above 0, i.e. 0.001 or 10 C

Thanks Endlessness for letting me know im not alone hah

And thanks for the answers Infundibulum!

Would I be right to think its decieving to call 0 the freezing or melting point if somethings not going to fully freeze or melt? They should call it the transition point or something....

True that, especially if you think that the Celsius scale is supposed to be constructed around the freezing/melting and boiling temperatures of water.