How cold is my ice?

theTinker

I made a nice cold glass of coke yesterday and put some ice into it.

And thought, hmm i wish ice was colder so it would cool more stuff before melting.. Then i realised, it might be.

If i put my fridge at number 1, it barely makes ice.
If i put it at 2, it makes ice.
If i put it between 3-6, will my ice be super cold?

Can i cool something down more and for longer if i make ice at a higher setting in my fridge?

Thanks scientist people.

YFlyer

Use a thermometer at the different settings to measure any changes in temperature.

Podge_irl

The ice will be colder alright. The majority of the cooling process from ice comes from it turning from solid to liquid though. Having slightly colder ice will have a negligible effect.

theTinker

hmm so my ice will be colder but not make much of a difference to cooling my drink? Is this in temperature or in longevity?

I can imagine that as the ice has turned to liquid, it would indeed cool my drink alot instantly as the conductivity transfer of heat would be great to a liquid.

I think i may need to give this a spin later on when im home. 2 drinks. 1 with a day in a normal freezer, and 1 with a day with it super cold setting on.

If i throw a party, it might be a good idea to turn the freezer onto super cold for a hour or so before its needed. for super cold drinks.

Thanks for the info so far.

Podge_irl

The latent heat of water/ice is significantly higher then the specific heat capacity. This means it takes an awful lot more energy to go from ice to water at 0C then it does for the ice to go from -1C to 0C. Orders of magnitude more. It's getting the ice to melt that does the majority of the cooling in a liquid, not warming the ice up.

You need a lot of energy to break the bonds in the ice that give it the crystalline structure. This only happens once the ice hits 0C. However, getting the ice up to 0C doesn't require anywhere near as much energy.

magicianz

It wont cool your drink a lot instantly, it will a bit but the main property behind the cooling effect of the ice is latent heat when a body changes state (eg from solid to liquid) =]

Energy is required to change the state of a body. To melt the ice cube and change it into liquid, energy must be given to the ice cube. The energy the ice cube uses is the heat energy in the drink. The heat energy is removed from the drink and the ice cube starts to melt into water, which is around 0 degree celsius. The heat energy removed by the change of state and the meltwater from the ice cube, cool your drink.

It can be hard to get your head around at first :P

FISMA

Picking up ice for a short period of time will not hurt your hand. It is cold, but not that cold.

Try picking up dry ice (actually don't). You will very quickly find out that it is very cold and it will quickly hurt your hand.

Ice can be cold or warm, so to speak.

Let's stick to what we usually call ice - frozen H2O.

"Water" freezes at 0°C = 32°F.

Under the usual circumstances, the "warmest" ice can ever be is 0°C. You can have colder ice, but not warmer.

I believe dry ice is about -79°F which is why is that much colder and dangerous to handle.

ianobrien

But don't forget about the triple point of water. It's the one temperature that the compound can exist in it's solid, liquid & gaseous state. For water, it's 0.01 Celsius.

OP, the specific heat capacity of liquid water is 4200(ish)J/KgºC, ie it takes 4200 Joules of heat energy to heat 1kg of water by 1ºC. The specific heat capacity of ice is 2100J/KgºC, half that of water. The latent heat of fusion of water is 334,000J/kg, ie it takes 334,000 Joules of energy to convert one kilo of water to ice at 0ºC, and vice-versa

So, as you can see above, the majority of the cooling of the glass of Coke comes from melting the ice, not by having much cooler ice in the glass.

SOL

Three things spring to mind:

firstly it is likely that your coke with the ice will be atleast a small ammount below zero because then you add other things to water it's freezing point lowers so the ice melts (taking in all the thermal energy in the rest of the drink) at a lower temperature.

Two, since there is a certain temperature that your drink freezes at, you know that it is never colder than that unless it is frozen, and aslong as the icecube are still in it it is that cold, doesn't matter how hot or cold the ice was when it went in it wont' change the temp of your drink.

Finally though, you should try this: take some ice cubes and sprinkle a generous amount of salt on them and crush it up. Then check the temperature, you can get as low as -20C using this, even if the ice you had was at 0 to start with. What I said in point one explains this. The same applies for ice and ethanol (or vodka), you can get ice down to -50 and below with the right things chemical even if it started at 0!


Here is a link for someone doing the experiment in a lab: http://www2.uni-siegen.de/~pci/versuche/english/v105-2.html

SOL

Also, as for the dry ice, not that it is to be recommended but you can easily hold it aslong as you let is roll around in your hand, it forms a gas layer which means it doesn't cool your hand as quickly as it might otherwise.

Gregsor

Interesting read,wondering where one could get a small amount of dry ice?

There is an Irish company that do delivery option online but i really don't need much,thanks.

theTinker

wow Thanks for all the responses. I get it now. And see why my idea would have so little effect.

I didnt realise that the state change from solid to liquid required any more energy than heating liquid water at 1C to 2C.
If im correct in my reading. It takes more energy to change the state of the ice to liquid than a simple 1C change, and this energy is sucked from the drink, which is why it has a dramatic cooling effect.

Its not the same as simply adding a cooler liquid to a warmer drink.

Thanks alot.

clearz

Thanks this makes a lot of sence. My aunt uses them plastic ice cubes which are filled with water that don't melt. I always found them absolutely useless and had figured before that the main cooling had something to do with the melting process of normal ice.