how does antifreeze work chemically?
441058
It forms an azotrope, an intermediate component that has a lower freezing point than either of the two parts.
1052558
In freezing, the latent heat of fusion in the water molecules is released with out the water changing its temperature. The molecules lose average kinetic energy, and start behaving like particles in a solid, with minimal vibrational movements and close seperations. The reverse process is melting, where latent heat of fusion is absorbed by the water molecules, increasing average kinetic energy which is used to break bonds between molecules so they start behaving like particles in a fluid.\n\nThe transition from liquid to vapour, and vice versa follows a similar path, except the heat energy required for the process is in this case called latent heat of vaporisation.
1028715
anti freeze proteins are protiens that are produced in fish, insects etc in extreme cold condition. one of the example of a fish which produces AFP is TELEOST fish.\nwhat these protiens mainly do is that they are capable of lowering the freezing point of a solution in a non-colligative manner by lowering the freezing point to the melting point.\nthe difference between the melting point and the freezing point is known as THERMAL HYSTERESIS.\nthese proteins prevent recrystallisation of ice , which is a thermodynamically a favoured process which involves the growth of large ice crystals at the expence of smaller ice crystals..... this is how these protiens work...
684151
The freezing point of pure water is 0°C, but that melting point can be lowered by the adding any solvent such as a salt. Depending on the amount of salt the freezing temperature of a saline solution can range from below 0°C to -21.1°C. The frozen solution is a mixture of separate NaCl·2H2O crystals and ice crystals, not a homogeneous mixture of salt and water. This heterogeneous mixture is called a eutectic mixture. \nThe use of ordinary salt on sidewalks is effective because it requires a colder temperature to freeze water and it is a cheaper alternative to other solvents or methods of ice removal.
933014
All decent explanations so far; I hope I can add to what has already been posted.\n\nLiquid and Ice most definitely can exist at the same temperature and Ice can be and often does get colder than 0C.\n \nFirst of all the Triple Point of water is the pressure and temperature at which Ice, Liquid Water and Water Vapor exist at the same time in equilibrium.  Vapor is the right word, not steam although you can argue that the only time that Water Vapor and Steam are the same thing is at a very low pressure.  The Triple point of water only happens at a near perfect vacuum, 0.0063 ATM to be precise.\n\nAdding Salt to water will lower the freezing point, but then it isn't water anymore, it's salt water.  Even so, Liquid Salt Water and Ice Salt Water can also exist at the same place and time at the same temperature, slightly below 0C.  But let's stick to water.\n\nIce can easily be lower than 0 degrees.  Consider a bucket of water, liquid water sitting outside and the air temperature is -10C.  Little by Little, as the liquid reaches 0.0098 C, liquid starts to become ice.  The ice crystals form in the bucket, around the walls of the bucket and on the surface first.  The air is still -10C so the bucket, the liquid and the ice will keep getting colder.  The ice on the surface will drop to slightly below 0C but very slowly since it is still absorbing the heat of the not-yet-frozen water.  Eventually, the entire bucket of water will be frozen and will be just below 0C.  First the walls of the bucket will reach -10C (same as the air tempertaure).  The ice near the walls of the bucket and on the surface will reach -10C first, continually absorbing the heat energy from the relatively warmer ice near the center of the bucket.  Until finally, the entire bucket of ice is steady at -10C.  That is until the sun comes out or the day gets warmer.\n\n\nAnd by the Way, dry ice is not water, it's frozen CO2 (Carbon Dioxide)\n\nOne more thing, at a near perfect vacuum, you can actually cool liquid water to less than 0C without it freezing.  Never tried that but I did accidently freeze a beer last night...
372400
Automatic defrosters remove ice through sublimation.  The ice-cubes actually get smaller;  they do not come through the process unscathed.
432980
Look in the index of an introductory chemistry text for "colligative properties", "freezing point depression", or "boiling point elevation".  Simply put, the water molecules prefer to orient themselves around the sodium and chloride ions instead of each other.  This lowers the freezing point (more energy has to be removed from the system to slow down the molecules enough to be in the solid state.  This effect also accounts for the boiling point elevation (salty water boils at a higher temp) and for the same reason.
6303
Silver iodide is released into the clouds which baically grabs hold of supercooled water droplets (water that is colder than ice but still liquid) and if the conditions are right, the supercooled water droplets will freeze, attract more water droplets and eventually form snowflakes....\n\nPlease understand that this is a very basic description but gives the idea...
10363
The freezing point drops, by the Clapeyron equation. See the attached reference for details. \n\nThe answer above is dealing with ideal gases, not liquid water.
668402
This is what I found when I googled- freezing point of gasoline\n\nWell, gasoline should freeze if you get it cold enough! Gasoline does not consist of a single kind of molecule -- it contains several different hydrocarbons (molecules consisting of hydrogen and carbon atoms). In principle, if you cool a mixture like this slowly enough, it will form a collection of different types of frozen crystals, with the freezing of each type of crystal occurring over a (different) range of temperatures. In practice, often such mixtures don't form crystals at all but just gradually thicken and harden as they get colder, forming something like glass- hard but without the regular crystal that make a true solid so different from a liquid. In a glass, on a small scale the molecules are still jumbled up like in a liquid.\n\nThe problem of fuel getting gummy and solidifying is more of a worry with aviation fuel. High-flying airplanes fly through very cold air (every time I fly and they show the outside temperature, it's -80 F!). And one of the last things you want to happen to an airplane is for the fuel pipe to freeze up. People add stuff to aviation fuel to keep this from happening. Piston-powered propeller planes sometimes have isopropyl alcohol or other compounds added to prevent freezing.
726926
Salt... When applied to ice, the salt (NaCl) dissolves into the water creating a salt water mixture which has a lower freezing point than pure water.\n\n10% salt solution freezes at 20 F (-6 C)\n20% salt solution freezes at 2 F (-16 C)\n\nSalt becomes less effective at temperatures below 0F (-32 C).\n\nEnjoy!
680279
Technically a process can require the addition or extraction/removal of heat ENERGY.\n\nI cannot off the top of my head recognize a chem formula any longer, but adding oxygen to any system is oxidation and generates its own heat.  Tehcnically even iron rusting generates heat, just a very small amount, since any metal "rusting" is just it oxidizing.  \n\nAs far as the ice cubes, simply the removal of heat will not cause water molecule to become ice crystals,  I apologize, but I forget why.  I remember an experiment I saw and tried.  In a very clean container, pour distilled water. Now cover that container with another container that does not touch the first.  (Like putting a big bowl over a smaller bowl with the distilled water.  The water stays liquid all the way down to around -20 C.  But if you damage the stablility of the bowl by say gently tapping the side, the water will then turn to a solid.\n\nSnow in clouds form when the water molucle has a dust mote or other item to cling to and begin forming the ice crystal which eventually gets heavy enough to possibly fall all the way to the ground.
1003569
Dry ice is produced by compressing carbon dioxide gas to a liquid form, removing the heat produced by the compression and then letting the liquid carbon dioxide expand quickly. This expansion causes a drop in temperature so that some of the CO2 freezes into "snow", which is then compressed into pellets or blocks.
415970
I don't have a scientific answer for you, except to say that's just how it works. You could say it's the same reason that water expands when it freezes, as opposed to almost everything else which contracts.
89574
The chemical reaction from adding\nsalt lowers the temperature in which water freezes.\n\nThat is why they throw in onto the roads in areas of winter freezing.
86483
Actually, Gonpatrick, the original question is quite correct: Unlike most substances, water does actually expand when it is cooled, over a narrow temperature range from about 4 degrees C to 0 degrees C (the freezing point.)  This is why water freezes from the top down: the cooler water that is closer to freezing is less dense than, and so floats above, slightly warmer water.  (Above 4 degrees C, water expands when it is heated just like most other substances.) When the water freezes it expands some more, which is why ice floats.\n\nThe reason why it does this has to do with the way water molecules are put together.  The two hydrogens and one oxygen in H2O are assembled in a triangular pattern, with one part of the molecule more positive and the other more negative.  Above 4 degrees C, the molecules move freely around each other, but when it gets close to its freezing temp, the molecules start to align themselves with the positive part of one molecule near the negative part of another, ultimately forming, when it freezes, a hexagonal pattern.  This arrangement takes up more room than when the molecules are free to move around.
361464
the principle is by compressing a coolant, and injecting this coolant into a small pipe, the size will minimize heat built up, as the coolant moves around the pipe or coil, air is blow into this coil which result into cooler air.\n\nThe coolant is then compress back to repeat the process.