Freezing Point of Water

Yes.

Salt water for example.

Right. Pure water freezes at 0°C.

Water with minerals gets colder before it freezes.

That's why we put salt on ice when we freeze ice cream. It melts the ice sooner and makes the water colder.

Very good, but almost too succinct.

Not really. What makes the most difference with inorganic solutes is the ionic nature of the dissolved substance (and most minerals that dissolve in water to any significant extent are ionic) as well as the concentration. So water that is saturated in dissolved iron won't make much difference, while water that is saturated in dissolved salt is another story. Are you getting your water from a well or a ditch at the side of the road?

Isn't salt a mineral? It can be found in concentrated form in the ground in many places, Just like iron and many other minerals.

min·er·al /ˈmin(ə)rəl/Noun: A solid inorganic substance of natural occurrence.

Salt certainly satisfies Google's first definition of mineral.

Salt is certainly ionic! So your "Not really" simply does not make sense!

Yes, I probably should have put "Not necessarily to any significant amount".

There seems to be a lot of references to salt in replies to this thread- my point was that the OP did not ask about salt water or specify any mineral in particular. In view of that, hard water from a well won't exhibit much change in the freezing point while brines obviously will. Again, the result depends mostly on the type and concentration of the minerals so you can't simply say yes or no to it making a significant difference.

Just to prove a point, the water does not have to contain ionic substances to have a depressed freezing point (and elevated boiling point). Ethylene glycol, propylene glycol, alcohol(s), sugar(s), and other soluble compounds that are certainly not considered to be ionic will do. The osmolality of a solution is defined as the freezing point depression for a solution of that solute in water at a given wt %, Δ, times 1.86.

Thus a molal solution of a given solute will depress the freezing point by 1.86 °C.

The boiling point elevation varies by a different (and distinct) amount.

That is true but as the OP's query specified minerals (which by their nature do not have the hydroxyl and other functions of organic chemicals that also contribute to this effect) I didn't consider it.

Lovely, Mikero!

The attaribute - elevation in boiling point and depression in freezing point - is used to determine the molecular weight of salts. The change in melting/ boiling point is related to the Molecular weight of the dissolved salt. Please recall. A Beckmann's thermometer is required for measuring the small difference in the melting/ boiling points and this has to be duly caliberated.

Keep it up!

Where in nature do you find pure water?

I believe a cirrus cloud has less impurities than any chemist's distilled, purified water.

"Where in nature do you find pure water?"

Rain is pretty close, it's probably about as pure as you'll find.

Nope.

There is one place place one could debate that pure water exists. The water found in the water of crystallization. I say this only because at an atomic level my statement excludes the encapsulating crystal structure thus that trapped water is pure. One cannot acquire this water in any fashion without it quickly becoming impure so it can be equally said that this is impure, too.

Also, this water never freezes while trapped in the crystal lattice.

antartic seems to me you would find pure water

Nope.

As Gene stated; if it weren't for "Condensation Nuclei", it would never rain in the first place! Therefore, impurities are a necessary part of the equation.

Good Answer. For the OPs (and maybe others) benefit, if pure water was left in an open container, it would relatively quickly absorb O₂, N₂, and CO₂ (among several other minor pure atmospheric constituents, as well as various pollutants) from the air, not to mention dissolving container material (as you said).

Great rhetorical question ozzb! PURE WATER IS NOT FOUND IN NATURE!

Nowhere in this universe, though the closest approach is the ultrapure water used in silicon chip manufacture. This water is manufactured by removing substances. Residual impurities can be expressed in fractions of parts-per-billion. In that respect, ultrapure water is the purest substance in the universe.

Thanks all. I have for-filled my daily quota of new knowledge. This forum is better than going to school.

for-filled? fulfilled maybe?

Since it's hyphenated, to me it means forum-filled learning as well!

Well said. This forum is better than going to school.

Dear Mr. ronseto,

Yes. Pure water, without any dissolved salt will freeze at 32 Degrees Farenheit or Zero Deg.C.

If some dissolved salts are found in the water, the freezing point will vary - depending upon the dissolved salt content(s).

The higher and higher is the salt content, which means the igher and higher concentration, lower and lower will be the Freezing Point.

Salt Spraying on the Road - during winter is for lowering the Freezing point. If I remember, correct - the name of the salt sprayed on the road is ROCHELLES SALT.

Thanks,

DHAYANANDHAN.S

In our area, the salt they put on the roads is plain unpurified sodium chloride.

Potassium sodium tartrate is a double salt first prepared by an apothecary, Pierre Seignette, of La Rochelle, France. As a result the salt was known as Seignette's salt or Rochelle salt. Wikipedia
Formula: KNaC4H4O6·4H2O
Molar mass: 282.1 g/mol
Boiling point: 428°F (220°C)

Melting point: 167°F (75°C)

Rochelle salt would be much too expensive to use on the roads. 50 or 60 years ago we used Rochelle salt to make homemade piezoelectric transducers. I've never been aware of it being used for anything like road salt.

In 1948 the standards were revised for the "triple point". It was internationally agreed that pure water actually freezes at 32.018°F (0.01°C)

Sorry to be a pedant about this but it is early Sunday morning here, I should still be in bed, but I have to take my son to the airport. If I am up and suffering, I feel the need to spread my suffering to you lot.

The freezing point of water can vary greatly,depending on pressure,minerals, and other factors.

32F or 0 degrees C is actually the MELTING point of ice, not the freezing point of water.

Water can be supercooled far below 32F if using very pure water in a very clean glass or beaker.

Try this:

Put distilled water in a very clean glass and cover it.Put it in your freezer over night.

Take it out the next morning, and it will still be liquid, if it has not been agitated or disturbed.

Now, tap the glass sharply on the side with a spoon,and watch the ice crystals form from the impact zone.Ice must have a starting point to form, such as the cavitation bubble just formed, or a dust particle in the clouds.

The temperature of the water will increase until it reaches the normal freezing point.It will then continue to rise to the melting point of 32 F.

This is what is happening when you pop the top on a very cold cola, and the contents begin to turn to ice.

This same characteristic of super cooling is used in heat packs,the type where you activate a "clicker" and it begins to heat up.

To reactivate, you heat it up until all the crystals are melted.

This is a concentrated solution of sodium acetate, if I remember correctly.Room temperature is far below it's normal freezing point.When it changes state,from liquid to solid, it must give up latent heat.This is the heat you put in when melting the crystals.

When the solution changes from liquid to solid, latent heat is released.Same with the water ice.This latent heat is the amount of heat required to change the state of matter from liquid to solid, or liquid to gas, or vice versa.

I hope I go that right, too sleepy to verify it with google, but I am sure someone will....Goodnight...

Now! Clear as mud?

The reason for the question is: When the temperature drops to around freezing, will my pipes freeze at 32° or do I have some leeway before freezing bursts the pipe?

Are the water pipes buried below the local frost line?If not it will take several days for the temperature to drop to below freezing, but they will eventually freeze of there is no water flow through them.

If the pipes are in an unheated building or residence, it is possible, but not on the first night of cold weather.It could take several days, depending on many factors.

If you are concerned about the ones in the house where you live, a good policy is to flush the toilet a couple of times a night.This will keep fresh water from the mains or well in the pipes and prevent freezing.At my age, I have no problem getting up that many times at night.

Unless you've moved from outside of Biloxi Mississippi there is no risk at all. Now if you're concerned about your unoccupied summer home somewhere farther north that was not winterized by draining your pipes then you could have a problem. As HTRN mentioned it will nominally take several days of below freezing outside conditions to freeze burst pipes. (Did I just coin a phrase?) If you are worrying about the outside faucets of an occupied and therefore heated house then there is a remote chance to freeze burst pipes, depending on location and duration of cold.

It is not the pipes freezing that causes them to burst, it is the pipes thawing. Water normally contracts as the temperature drops, but between 39°F (4°C) and the freezing point it expands. When it is about to freeze (as the temperature drops) this is not a problem because the water is just displaced back up the pipe. As the water starts to thaw (when the temperature rises again) sections of the pipe are still blocked by ice so the expanded water has nowhere to go. The expansion builds pressure and this is what bursts the pipe. If your pipes do freeze. Open a tap and apply heat from a hair drier to the pipe starting from the tap and slowly move it progressively towards the frozen zone. The melted region between the frozen part and the tap allows a path for any pressure to be released and the pipes will not burst. This advice does not work if you cannot get access to the pipe, but it is a good idea to leave taps on frozen pipes open on the chance that this will provide an escape route for any pressure build up during a thaw.

You're all wet, I'm afraid.

It's not the thawing that bursts pipes, because ice contracts when it turns back into water.

You've identified another anecdotal fallacy. The pipes do burst when they freeze. However, until the ice thaws the water pressure does not reach the ruptures in the pipe.

Try again. Ice expands from the freezing point to about -4 Celcius, when it begins to contract again. There are 3 solid proofs for this- broken pipes, the "knee" at the triple point of water, and the very little known fact that ice floats on water.

I guess that is why icebergs sink in Antarctica when calving from a glacier. The temperature there is so cold that the salt-less ice is denser (takes less space) than sea water. Hmm, that's not what the link says happens.

Sorry, where is the bit about them sinking? I don't see it in the link.

Ahem, I did say that link does not say that the ice sinks. Would you care to hazard a guess why the extremely cold glacial ice floats?

OK- guess I misunderstood your post.

I have to agree with Lyn and Redfred.

The density of ice is 0.9167 g/cm³ at 0 °C, whereas water has a density of 0.9998 g/cm³ at the same temperature.

As the definition for the Specific Gravity for all substances is based on the standard that water has a density of 1gm/cm³ at 0°, are we to assume that the published value of Specific Gravity of all substances other than water is incorrect?

Depending on the situation even running water can freeze given a fast enough temperature change, like living in north Dakota and its -40 with. - 85 wind chill lol, i own a construction company and travel extensively, i usually live in an RV, after we set it up, we take 2 inch foam boards and make an enclosure around both the incoming water and the storage tanks, and then put a heater inside and close it up, if i lose power and its a cold day, i have had the pipes freeze in a couple of hours, even if still running slowly, but they also usually thaw fairly quickly if you catch them in time, usually with little to no damage, so it all depends on where your pipes are located lol

Obviously you have never made ice cream in a churn. What is the world coming to? That was wintertime Saturday night entertainment when I was a child. Put the ice cream mix in the metal container with the beaters - submerge in well salted ice and water mixture - attach the hand crank to the top - crank for about 1 hour or until your dad couldn't hardly turn the crank anymore. Ice cream froze because the salt/water/ice mixture was colder than 32 degrees F.

Gents,

We're talking about drinking water in a pipe.

Not distilled water, not water with antifreeze in it.

Just plain old water water.

But can dirty water freeze in the vacuum of space?

Hail yes!!!

Halley's yes.

Indeed. http://iopscience.iop.org/1538-3881/144/4/97

and wierd ice at that: http://en.wikipedia.org/wiki/Amorphous_ice

So can you tell me, why does the last dirty snowbank in spring take longer to melt than anything else?

I do not know why but I do have a plausible reason that requires funding to perform a rigorous study to validate.

The dirty snowbanks are predominantly snow compaction's from a clearing area of a roadway, sidewalk, parking space and similar types of circumstances. As such they are a summation of a larger amount frozen water over the area they occupy than the snow present over the unplowed areas. When thawing happens, quickly the plowed areas drain and evaporate to ice/snow free areas since only salty residues remain. The unpacked areas next clear at their natural rate. Next the packed but unstacked regions (foot prints) clear. The infrared heat transfer through compacted snow (ice) into the soil is more effective than the infrared scattering of fluffy snow. As such the infrared energy of a spring like day transfers more into un-compacted snow than compacted snow. Lastly comes the dirty compacted snow because these heaps were once significantly large piles of snow in the first place. It will take considerably more total energy to change more snow than less snow.

To support research into this unproven hypothesis, please send your funding in care of Quentin Robert Denameland to your local philosopher appreciation society.

_{Grumpy Jack's in Port Jefferson.}

I wasn't all that surprised to hear that there are super cold forms of ice which is classified as a metal. Of course without the appropriate funding to test, I simply accept that the icemetal concept is reasonable because of bouncing an iron shovel off last week's melted and refrozen snowload, or one of the aforementioned "dirty banks".

One would suspect freezing, but I think of a more sublime idea. Slow vaporization.

Water can't sublime unless it is already frozen...

I think the real question here is: Can you have liquid water in empty space? I believe the answer is: Not for long!

Probably about the same period of time one could have liquid nitrogen on a hot skillet.

!

This belongs in the Very Very BAAd pun section!

There's no such thing as <...plain old water...>, though. Every water is different.

Comet?