What Temp Is Ice Water?

Yeah, I know it's theoretically 32*, or maybe it's not. Is it 32.5*, or more like 33*, or even warmer than that?

I have to tweak a digital down some, and it occurred to me since I am adjusting a xxx.x resolution thermometer, that maybe I should ask instead of assume the temp is exactly 32*.

And how much does water purity matter, not talking about sea water or something that rich of a solution?

Does elevation affect the temp? I am just below 1000' above seal level, but it occurred to me that elevation is an issue for those in the mountains...

If you put a bunch of ice cubes in a minimum amount of water, just what temp is it going to be?

I've always used 32°F for a glass of ice with little liquid water in it.

Your temperature estimation device will be fairly close then... it's all relative to your measuring device anyway.

32 if it's mostly ice and water filling the gaps.

The best method is to make up a crushed ice and water solution. That's effectively 32 deg. F. Even if it's off by .1 or .2 degrees, that's still at or below the margin of error on normal thermometers.

-Steve

32F, 0C - it takes the heat of fusion to make ice so the temperature doesn't change but more heat is released as it changes phase - make sense?

It can't be exactly 32. If it was then it would not be water. I would say it depends on the amount of ice to water and how long they have been mixed together. It is probably under 33 though. Also the amount of TDS (total disolved solids) in the ice will make a difference. I don't think elevation will matter though. I think elevation only matters with boiling but I could be wrong with that.

The freezing point of liquid water is 32°F. The melting point of solid water is 32°F. Without considering temperature equilibrium throughout any given vessel of ice water, it's temperature will effectively remain at 32°F until all ice is melted. This is due to the latent heat of melting. This is what mandoman is getting at. Because temperature can vary in a vessel (warm spots), in the real world, Bobby_M has it correct.

This thermometer is used only for cheese, so it only has to read up to 108*, but mainly at mid to upper 80's. But at this small of a temp range, a degree or two is worth knowing.

I guessed it would be about 32.5*....as the water is getting cooled by the surface of cubes, but getting warmed by the surface of the container.

lehr, you're on >ignore<.

Henry Hill said:

Does elevation affect the temp? I am just below 1000' above seal level, but it occurred to me that elevation is an issue for those in the mountains...

Click to expand...

It does, but not in any practical sense. The variation is less than one hundredth of a degree per atmosphere of decrease in
pressure.

menschmaschine said:

The freezing point of liquid water is 32°F. The melting point of solid water is 32°F. Without considering temperature equilibrium throughout any given vessel of ice water, it's temperature will effectively remain at 32°F until all ice is melted. This is due to the latent heat of melting. This is what mandoman is getting at. Because temperature can vary in a vessel (warm spots), in the real world, Bobby_M has it correct.

Click to expand...

Yeah, one of the crazy properties of water. Also, that its solid form is less dense than its liquid form, making ice float.

-Steve

If you want to do this right, you need to setup a triple-point cell. The temperature will be 273.16K @ 0.6117 kPa

Henry Hill said:

I guessed it would be about 32.5*....as the water is getting cooled by the surface of cubes, but getting warmed by the surface of the container.

Click to expand...

No, its 32 degrees. It takes heat to melt change the ice to water. IE, water is 32 degree ice + heat required to melt.

Your water will be 32 until there is no ice left.

Use an insulated container like a styrofoam cup or a travel coffee mug, put in the crushed ice with enough water to just cover the ice and stir. Let it sit a minute or two and then put the thermometer in the mixture and stir with the thermometer until the temp doesn't change anymore. The real temp of the mixture will be 32 F and because you are stirring you don't have to worry about warm spots.
You could a similar thing with boiling water to make another calibration at ~212 F, keep the pot on the heat and keep stirring once it is boiling. At 1000' elevation the boiling point of water is ~210.3

Everything I've read in this thread so far assumes you're dealing with distilled water. If you have dissolved salts in the water that will lower the freezing point (and raise the boiling point). With enough salt in there, it's possible to lower the freezing point below 0 F.

Oh yeah, and you'll want to use distilled water for the test.

It will be 32.0, assuming everything's pure. We're talking about a phase change here, water can be either liquid or solid at 32F. As you warm ice up, it will hit 32F and stay there until it's all become water. I had an old chemistry teacher back in high school who put it this way, it's better to get hit with 212F water than 212F steam, because even though they're the same temperature, the steam has a lot more heat energy in it.

Scimmia said:

I had an old chemistry teacher back in high school who put it this way, it's better to get hit with 212F water than 212F steam, because even though they're the same temperature, the steam has a lot more heat energy in it.

Click to expand...

By definition of what temperature that is a wrong conclusion.

Synovia said:

No, its 32 degrees. It takes heat to melt change the ice to water. IE, water is 32 degree ice + heat required to melt.

Your water will be 32 until there is no ice left.

Click to expand...

I would rephrase that to say the ice will be 32 until there is no ice left. The could be higher.

It is not just phase change, but also phase change over time. I will use an illustration by exaggeration. Take some ice and put it on some concrete in the sun when its 90 degrees outside. The ice will stay solid for a couple seconds. That doesn't mean that the water around it or that the sidewalk is 32F.

Now, obviously in a glass of water the change over time slower, but the same principle applies.

Also, as was already stated, if the ice is melting, then there must be some place in the glass where the temperature is greater than 32.

Having said that, for all practical purposes ice water is 32F. Thermometer error and user error contribute more error than using ice water to calibrate to 32F.

I KNEW there was a topic here or I wouldn't have posted; LEHR!

My ice is softened well water, the tap water is also softened well water.

I am more likely to be changing phases than the water. :cross:

weirdboy said:

Everything I've read in this thread so far assumes you're dealing with distilled water. If you have dissolved salts in the water that will lower the freezing point (and raise the boiling point). With enough salt in there, it's possible to lower the freezing point below 0 F.

Click to expand...

all the way down to -6F

Not to over simplify but I think the real question is what is the temp. around the ice?
If the air temp is 60 degrees, the ice is melting but it is still 32. If the air temp. is 32 degrees, it is freezing.
The air temp around it is just the speed of the melting or rate of freezing.

PS. First time on this thread. Not a scientist.

lol,
I love the science forum.