it is said that foreign substances added to water will cause a freezing pt drop. is coffee a foreign substance
554284
Yes it is a foreign substance and yes it will lower the freezing point.
621743
We cannot make a substance cold. \n\nWe can remove the heat from one place to another.\n\n  What is the difference between ice and water?\n\nFrom ice we have removed heat. The water is water because we have not removed heat from it. \n\nWe should not say ice is cold when compared to water, because we have not made it cold but we have removed heat from it.\n\nSimilarly when we want some hot coffee, we should ask, I want a coffee in which heat is added because we cannot make coffee hot.\n\nThank you.
239534
because the impurities have low melting points under the ice , u got a compound not a pure material
108664
skin is primarily water so it stands to reason if too cold it will freeze as water does
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.
530844
What a good question!  I think it's due to our expectations.  Next time you drink your cold coffee, make yourself believe it was an iced coffee and see what your reaction is.
118956
Liquids expand when they freeze.
606548
Absolute zero.  There are ways to keep water from freezing using pressure, motion, impurities, and so forth.
1010626
Could be that different chemical compounds freeze at different temperatures.  Water freezes at a lower temperature than 36 degrees but not everything does.  That is also like why you put salt on ice to thaw it, it lowers the freezing point, so it has to be a lot colder before you get ice.
145784
Water expands when it freezes. The drink was mostly water. That broke the glass, but it brokr before the drink was completely frozen, so the carbonation caused the drink to spray all over the freezer.
813765
Yes the main ingredients of anti-freeze are in many over the counter medicines.  Used as preservatives in most cases.  This country allows all sorts of crap in our foods that shouldn't be there.  Look for Propylene Glycol, or Ethylene Glycol listed in the ingredients list.  Not to mention that BHA and BHT which are in much of our food is "Rubber preservatives" invented in WWII to keep synthetic rubber from deteriorating in our tires when our supply of natural rubber was cut off during the Pacific war.
557600
Water is one of the few substances that expands as it freezes.  From 4 degrees Celsius down to 0 degrees water expands and as a result the frozen solid form is less dense than the liquid form and that is why ice floats.\nThe water in the soft drink expands and the can cannot hold the increase in volume.
1118068
The degree in which ice is frozen at is variable-although-just regular ice in a glass of water does taste different-the composure and breakdown of the of the cform composites found in the water freeze via vast degrees we normally wouldn't taste unless it's frozen...!?
909795
Adding sucrose to water is a VERY Endothermic reaction.  That means it requires heat to make the sucrose dissolve.  If you added a bunch of sucrose (sugar) to a glass of water at room temperature, the temperature of the water would drop and the solution would become cold as the sucrose dissolved.  \nSo, putting sucrose on ice should either do nothing since there is not enough energy to make it dissolve and interact with the water molecules ... or .... if there was enough energy, the sucrose would start to dissolve causing the ice to become even colder!  Adding sugar to water makes the temperature drop like a rock (This is fact), as for ice I would expect the same thing....that's only my opinion, I could be wrong.
229195
When you add a salt to water and the container feels cold, yes, an endothermic reaction is taking place.  The solution is grabbing heat from the surroundings to get the salt to dissolve.  When you add a salt to a pure solvent (say, water), the freezing point will go down and the boiling point will go up.  That's because the vapor pressure of the pure solvent is lowered (this would be easier to explain with a phase diagram).  Remember, the definition of BP is the temp at which the solution's vapor pressure equals the external pressure.  By lowering the vapor pressure, the whole phase diagram shifts...BP to the right (higher), FP to the left (lower).  You may want to check out a intro level chemistry text or at least draw out the phase diagram to see more clearly what gets lost is just words here.  Did you ever try boiling water without heating it?  If you have the means, hook up a vacuum to a flask of water.  You don't change the vapor pressure of the water, but you reduce the external pressure enough so that the water does boil.\n\nOne more thing...  The change in BP and FP is related to how much salt is added to the solvent:  delta T (change in T) = Km  where K is either what's called the molal freezing-point depression constant or molal boiling-point elevation constant;  m is the molality of the solution defined as moles of solute (salt) / kilograms of solvent. By knowing the constant for the solvent, how much solvent you have and how much solute you add, you can predict by how much (in degrees (C) the BP or FP will change.\n\nI would just like to add a couple of more comments... The reaction that is endothermic in this case is  NaCl(s) --> Na+(aq) + Cl-(aq)  ...  The reason that the freezing point is lowered is as J. Schultz said - the vapor pressure is lowered ....  However there is a simple analogy (that may be useful) which gives a simplified picture ... Freezing involves the water molecules becoming very ordered in crystalline lattice...  However when there are foreign particles such as Na+ and Cl- ions in the water they hinder the formation of the crystalline structure because they interfere with the intermolecular forces between the water molecules.  Also, the freezing point depression and boiling point elevation are called colligative properties...  that is, they are properties that depend only on the number of solute particles and not on their chemical properties...  The third famous colligative property is osmotic pressure.
408269
It actually can be, believe it or not.  It has to do with hydrogen bonds.  Water exhibits very strong hydrogen bonding due to its polarity, and in order to freeze, these hydrogen bonds in liquid water must be broken.  In hot water, more of these bonds are already broken, so a quick drop in temperature could allow the water to freeze before the hydrogen bonds reform.\n\nNote that this is strictly a kinetic or time-based effect.  Thermodynamics dictates that cold water will freeze faster since a smaller energy drop is required, but in some cases it is entropically favored for hot water to freeze faster.\n\nAlso note that stirring the water vigorously will also break hyrdogen bonds, so stirred cold water will almost always freeze before stirred hot water.  You will only observe the phenomenon of interest when the water is fairly pure and undisturbed, and the temperature drop is rapid enough.\n\nWe discussed this very problem in my graduate-level thermodynamics class.
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.