Which will freeze first...hot water or cold water?
353832
The answer depends on many variables, including:\n   - How hot is the hot water?\n   - How cold is the cold water?\n   - How cold is the freezing environment?\n   - What is the humidity in the freezing environment?\n   - Are the water containers covered or not?\n\nThere is a famous experiment in which boiling water in an uncovered container exposed to dry, barely-below-freezing air froze before a container of the same amount of room-temperature water in the same conditions.\n\nThis only happened because much of the hot water evaporated in the first few minutes, leaving a much smaller mass of water in the "hot water" container than in the "cold water" container.\n\nIt is not hard to show that a small mass loses heat faster than a large mass. So, ultimately, the "hot water" froze first.\n\nIf you run the same experiment with sealed containers, the cold water freezes faster because it has the same mass and less heat to lose before freezing.
892823
Yes, the water will freeze if no heat is added as the pressure is lowered. I have seen this done in a physics class. A dish of water is placed in a vacuum chamber and the pump is started. As the pressure gets lower, the water boils, but it is boiling at low temperature, it isn't getting hot. After a while, the boiling water freezes solid.
489650
No. Hot water will boil quicker because it is closer to water's boiling point. At sea level the bp of water is 100 C. (The boiling point is a little less at higher elevations). Once it gets heated to that it doesn't get hotter but rather it changes to a vapor. Cold water requires more energy over a longer period of time to heat it to the required temperature to reach its boiling point.
685755
Ice water.  Ice is the solid phase and the water is the liquid phase.
237724
Infact, FLOWING water does freeze. but FLOWING WATER cannot freeze completely at 32 degrees providing it is attinaing warmth from somewhaere else. If you check the temp of a glass of ice water. It is 32 degrees but it is not completely frozen! 32 degrees is when ice begins to form &/or can sustain itself. The only reason your ice melts is because the water temp surrounding the ice is conducting the heat of the room which in turn tries to rise the water temp. While the ice is trying to hold the temp @ 32 degrees. Eventually the ice will melt; it releases cold in the form of water, to cool the water surrounding it. But because the warmth of the room is indefinate, the ice will eventually melt away as it is unable to hold the temp. Now if you put you ice water in a freezer that's set at 32 degrees. Your water will freeze. Because the water is no longer drawing the energy it needs to sustain its heat so the ice wins and freezes the water. \nSo how the heck does this pertain to rivers and moving water?\nMoving water is gaining warmth from the ground and the air. but becaue its moveing the temp of 32 degrees is not easily sustained so the ice melts and refreezes as it travels, because the weather changes and temps change ect. The only way to freeze moving water it to either:\n1. Have it be so cold that the water nearly immidiatly freezes (well below zero) or \n2. Have a sustained temp of below 32 for several hundreds of miles. \nNow if you put the water in a water rocker and put it in the fridge at 32 degrees it will freeze solid at some point because the temp is sustained and really how long it takes for it to freeze is the ultimate question. which depends entirely on the temp.\n-hope that helps
461815
you do the experiment yourself places a cup of cold and hot water in your freezer, the hot water will freeze first, the\nhotter the water the faster it will freeze
650071
cold water boils faster for the same reason that hot water freezes faster. I don't know what that reason is.
541637
Water will.  Soda has dissolved compounds that 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.
297542
well lets see, if cold water is anything above 0 Centigrade and hot water is anything under boiling....my money is on the hot winning. What I can not understand is why you asked?
100486
What I have always heard is that if you have been working outside alot, and you are hot, that you shouldn't drink really cold water because it can actually mess with your heart.  The cold water becomes a complete "shock" to the heart, and could do some bad for you.
105568
How about cold rose water?
209676
Neither can freeze.  Boiling water is 200+ degrees F.  Room temp is roughly 70 degress F.  Now, if you meant does something at room temp freeze faster than something that is at boiling (water), then the answer is, in general, yes.
552808
Write your own essay...but water freezes when it is cold and becomes ice which expands causing the pipes to burst, that's why they need lagging/insulating to prevent this happening.
292815
The answer is no and sort of.\n\nWater at 38 degrees (i.e. from the refrigerator) will freeze significantly faster (10 to 15 minutes faster) than hot water from the tap (125 degrees).  This is the range of temps most people are going to be dealing with.\n\nHowever, water at 190 degrees will freeze faster than water at 140 degrees.  The main reason is that more of the hotter water will evaporate before reaching freezing temps, so the ice cubes are significantly smaller - about 7/8ths the size of the cooler water.  Putting plastic wrap over the heated water reduced the time differential significantly.  \n\nI think the moral of this story is that you can get nearly any result you want by manipulating the conditions correctly.\n\nAlso, I feel the need to correct the second answer above.  Cooling is the process of slowing down molecular movement, not speeding it up.
825154
Sleet is a mix of water and snow.  Freezing rain is more interesting.  Usually water freezes at 0 degrees Celsius.  But if it's completely free of bubbles and dust particles that ice crystals can start to form on, like in the upper atmosphere, it can cool down to minus 40 Celsius before it freezes.   This is supercooled water.  The moment supercooled water hits a solid object, like the ground or an aeroplane wing, it freezes.  Freezing rain is supercooled water, and it's very dangerous to aircraft.
246690
Water actually freezes on the top, around from the edges, first. Water also expands when frozen. As the water freezes inwards, towards the centre, a little hole is created in under the right conditions the expansion can create a frozen spike on the ice cube.