rusty@sdcarl.UUCP (rusty c. wright) (05/13/85)
well, now that we've beaten the boiling water issue to death;
one thing that i've always had trouble believing is the common
belief that if you use hot water for making ice cubes that they
will freeze faster. does anybody have any idea why they should
do that?
--
rusty c. wright
{ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!rustymorse@leadsv.UUCP (Terry Morse) (05/14/85)
In article <188@sdcarl.UUCP>, rusty@sdcarl.UUCP (rusty c. wright) writes: > one thing that i've always had trouble believing is the common > belief that if you use hot water for making ice cubes that they > will freeze faster. does anybody have any idea why they should > do that? I've been silent until now, but I can't take it any longer. Rusty, who writes above, should be skeptical. Asserting that hot water freezes faster than cold is a direct violation of the second law of thermodynamics. Asserting that cold water boils faster than hot is also a violation. If anybody believes any stories like the ones above, I have a great perpetual energy maching for sale cheap. If anybody has any cases that run counter to the second law, I'd love to hear them. They are always good for a laugh. But let's not clutter the net with them. [They don't call it a law for nothing] -- Terry Morse (408)743-1487 UUCP: { (ucbvax!dual!sun) | (ihnp4!qubix) } !sunncal!leadsv!morse UUCP: { allegra | ihnp4 | dual } !fortune!amdcad!cae780!leadsv!morse
stevep@haddock.UUCP (05/15/85)
/* Written 8:47 pm May 12, 1985 by rusty@sdcarl in haddock:net.cooks */
/* ---------- "freezing hot water" ---------- */
well, now that we've beaten the boiling water issue to death;
one thing that i've always had trouble believing is the common
belief that if you use hot water for making ice cubes that they
will freeze faster. does anybody have any idea why they should
do that?
--
rusty c. wright
{ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!rusty
/* End of text from haddock:net.cooks */
Is this true or just creative b.s. ?fred@mnetor.UUCP (Fred Williams) (05/16/85)
In article <188@sdcarl.UUCP> rusty@sdcarl.UUCP (Rusty Wright) writes: >well, now that we've beaten the boiling water issue to death; >one thing that i've always had trouble believing is the common >belief that if you use hot water for making ice cubes that they >will freeze faster. does anybody have any idea why they should >do that? >-- > rusty c. wright > {ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!rusty There is no reason why they should do that because they don't! Cheers, Fred Williams.
vch@rruxo.UUCP (V. Hatem) (05/17/85)
For God's sake, you *can't* freeze hot water faster than cold water! (for the same reason you *can't* boil cold water faster!) AGAIN: Newtons (thrid, I think) Law of Thermodynamics! which, stated roughly, says that an object (substance or whatever) that has mass cools (heats) in direct proportion to it's mass and the difference between the desired temps. i.e.: a large glass of cool water, when heated, has to increase in temp until 212 degrees is attained. The same mass of hot water has a FEWER number of degrees to increase. Freezing is the same way. The mass has to give off a good deal of heat (ie the surroundings must ABSORB a good deal of heat) in order to freeze hot water. The mass will actually give off a greater amount of heat when hot, but when the formerly hot water becomes the same temp as the cool water, the speed in which it gives off the heat is decreased (that's where the difference between the temps comes in) and is actually the same rate as a fresh glass of water from the tap with the same temp! (in other words, you just wasted time cooling the hot water to tap-temperature) If you have any doubts, mail me - if I get enough replys, I'll look up the formulas in my old chemistry book and post it. Vince Hatem Bell Communications Research rruxo!vch --- +----------------------------------------------------------------------------+ | The assumption that a whole system can be made to work better through an | | assault on its conscious elements betrays a dangerous ignorance. This | | has often been the ignorant approach of those who call themselves | | scientists and technologists. | | -The Butlerian Jihad | | by Harq al-Ada | | (Children of Dune, by Frank Herbert, p395) | +----------------------------------------------------------------------------+
mickey@illogica.UUCP (Michael Thompson) (05/20/85)
> > /* Written 8:47 pm May 12, 1985 by rusty@sdcarl in haddock:net.cooks */ > /* ---------- "freezing hot water" ---------- */ > well, now that we've beaten the boiling water issue to death; > one thing that i've always had trouble believing is the common > belief that if you use hot water for making ice cubes that they > will freeze faster. does anybody have any idea why they should > do that? > -- > rusty c. wright > {ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!rusty > /* End of text from haddock:net.cooks */ > > Is this true or just creative b.s. ? It's true. It does take less time for hot water to freeze than an equal volume of cold water. The rate at which a liquid approaches temperature equilibrium with it's environment is related to the difference in temperature between the liquid and it's environment. (Which do you think will have the most rapid temperature change? a) An ice cube thrust in a glass of cold water. b) A glowing, white-hot steel rod thrust in a glass of cold water. ) So, hot water cools ~faster~ than an equal volume of cold water because the temperature difference between it and it's environment is greater. "But... But... wait!", you exclaim. "There exists a point at which the ~hot~ water will be the same temperature as the cold! After that point the temperature difference will be equal and they should cool at the same rate." Yes, but the volume of the hot water will be ~less~ because some of the hot water will have evaporated by that time. Since there is less water to freeze, it freezes faster. -Michael B. Thompson {decvax,ucbvax}!dual!vecpyr!altos86!illogica!mickey
vallath@ucbcad.UUCP (Vallath Nandakumar) (05/20/85)
> well, now that we've beaten the boiling water issue to death; > one thing that i've always had trouble believing is the common > belief that if you use hot water for making ice cubes that they > will freeze faster. does anybody have any idea why they should > do that? > -- Hot water in the ice cube box will make the ice on the freezer floor melt and afford direct contact with the metal freezer floor. This will make the water freeze faster than if the ice cube box and the freezer floor were separated by a layer of ice (which is a good thermal insulator), as will be the case if you were to start off with cold water. Vallath Nandakumar
eric@rtech.ARPA (Eric Lundblad) (05/20/85)
No really, the hot-cold water effect is true. The principal that causes this also causes other things. For instance, wet wood burns better that dry wood. In this case, The oxygen molecules in the water helps out the fire, and we all know how much fire needs oxygen. The hydrogen molecule also doesn't hurt any. Does this clear things up? -- Eric Lundblad
bobm@rtech.ARPA (Bob Mcqueer) (05/21/85)
> In article <188@sdcarl.UUCP>, rusty@sdcarl.UUCP (rusty c. wright) writes: >> one thing that i've always had trouble believing is the common >> belief that if you use hot water for making ice cubes that they >> will freeze faster. does anybody have any idea why they should >> do that? > > I've been silent until now, but I can't take it any longer. Rusty, who > writes above, should be skeptical. Asserting that hot water freezes > faster than cold is a direct violation of the second law of thermodynamics. > Asserting that cold water boils faster than hot is also a violation. Oh boy, this one again. If we're going to have a prolonged discussion it belongs in net.physics, but I might as well say my piece. The "folk tale" here can be construed to be true, and nobody is violating the second law of thermodynamics. Remember evaporation. Nobody said you had to wind up with equal amounts of ice from equal amounts of water. The first time I heard this discussion I did a few experiments in my freezer, and sure enough, if you use shallow enough containers you can get warmer water to yield ice faster, and quite noticably LESS ice. I would also note that I was doing this in Colorado (dry climate), had to use shallower containers than the standard ice cub tray to obtain the effect, and didn't find that it was by much of a margin. Thing with "folk tale" type statements like this - they aren't carefully stated, and very often some secondary effect normally not considered in a "pure" theoretical model (and carefully screened from any controlled experiments designed to test the model) is being observed. If we want to extend this to a discussion of firewalking, experiment vs. theory, models vs. the real world, etc., let's move it elsewhere, and let people trade recipes in peace :-). Bob McQueer amdahl!rtech!bobm
bmt@we53.UUCP ( B. M. Thomas ) (05/21/85)
I know I shouldn't, but... If you start with, say, 140 degree water, and want to go to 32 degrees, then how are you going to get there without going through every lower temperature in between? And if it takes a certain time to get from 140 degrees to that lower temperature(say, 45 degrees), how is it going to take less time to go to 45 degrees and then to 32 degrees than to start at 45 degrees? A similar situation exists with the boiling issue. It is very true that the initial heat gain or loss is much faster with the greater difference in temperature, but once you've gotten to the other starting point, you've got exactly the same distance to go that you had from there. My mathematical skills are not what they should be, but I don't believe that you can prove that X plus Y is ever LESS than X, given that X and Y are both positive. Nor can you show that the distance from one point to another changes as a result of whether you start from there or are just passing through. I used to run a car wash. Now the folk around there were not the great erudite sort that we are communicating with here, but when they came up with that line, and I explained it to them, they eventually listened. Is it possible that there are some things so obvious that the more intelligent just can't see them? brian
js2j@mhuxt.UUCP (sonntag) (05/21/85)
>I used to run a car wash. Now the folk around there were not the great erudite >sort that we are communicating with here, but when they came up with that line, >and I explained it to them, they eventually listened. Is it possible that there > are some things so obvious that the more intelligent just can't see them? > brian No, it's just that you've made the unwarranted assumption that everyone on the net is more intelligent than the people who used to work in your car wash. -- Jeff Sonntag ihnp4!mhuxt!js2j "Time has passed, and now it seems that everybody's having those dreams. Everybody sees himself walking around with no one else." - Dylan
ken@alberta.UUCP (Ken Hruday) (05/22/85)
<the Obligatory first line> In article <334@we53.UUCP> bmt@we53.UUCP ( B. M. Thomas ) writes: >I know I shouldn't, but... > >If you start with, say, 140 degree water, and want to go to 32 degrees, >then how are you going to get there without going through every lower >temperature in between? And if it takes a certain time to get from >140 degrees to that lower temperature(say, 45 degrees), how is it going to >take less time to go to 45 degrees and then to 32 degrees than to start at >45 degrees? A similar situation exists with the boiling issue. It is very >true that the initial heat gain or loss is much faster with the greater >difference in temperature, but once you've gotten to the other starting >point, you've got exactly the same distance to go that you had from there. >My mathematical skills are not what they should be, but I don't believe that >you can prove that X plus Y is ever LESS than X, given that X and Y are >both positive. Nor can you show that the distance from one point to another >changes as a result of whether you start from there or are just passing through. > >I used to run a car wash. Now the folk around there were not the great erudite >sort that we are communicating with here, but when they came up with that line, >and I explained it to them, they eventually listened. Is it possible that there >are some things so obvious that the more intelligent just can't see them? > >brian OK. After reading the umpteenth million article on this topic I guess I should get my two cents worth in. I don't claim to know whether hot water freezes faster than cold but I have heard (many years ago) that hot water does freeze faster. The reason that was given (to the best of my recollection) is that when cold water is set to freezing, it first forms a crust of ice st the top of the tray. This is persumably because the ice at the top can release its heat into the atmosphere more readily. The consequence of this is that this crust becomes an impediment to the radiation of further heat from the tray. Hot water, on the other hand, tends to form a steeper thermal gradient in the tray with the water at the top being warmer than that at the bottom (much warmer than in the case of cold water freezing) - thus the formation of ice is different ie. it may be possible that ice forms from the bottom up (don't quote me on this). Thus heat from the tray can radiate more readily hence more quickly. This probably makes no difference in the case of metal trays but may make a difference in a tray with insulative value - ie. plastic. In any case, I don't think that the answer to the question is as obvious as some claim since you need to consider the effects of radiation and convection, and conduction - a simple comparison of temperatures is inadequate in any reasonable analysis of the problem. Sorry for being the umpteenth million + 1 person to clutter this newsgroup with unrelated trivia. P.S. While I'm at it, someone mentioned that they belived hot water contains less minerals than cold because they've seen mineral buildup inside a hot water tank. This buildup is most likely due to evaporation, and, hence, concentration of the minerals to the point of their precipitation on the walls of the tank. Ken Hruday University of Alberta
kaiser@roll.DEC (05/22/85)
Hot water will never freeze faster than cold water because of the greater temperature change the water must undergo to achieve this. However, freezing hot water does produce crystal clear ice cubes which can be nice.
sewilco@mecc.UUCP (Scot E. Wilcoxon) (05/23/85)
Now that the physicists are done with the laws of thermodynamics, can
an engineer take care of the difference in convection induced in the
freezer by water of different temperatures? (If I had a vacuum in my
freezer I'd also pass this to net.space...)
Scot E. Wilcoxon Minn. Ed. Comp. Corp. circadia!mecc!sewilco
45N03',93W15' (612)481-3507 {ihnp4,mgnetp,uwvax}!dicomed!mecc!sewilcogeoff@denelvx.UUCP (Geoff Baum) (05/23/85)
> > No really, the hot-cold water effect is true. The > principal that causes this also causes other things. For > instance, wet wood burns better that dry wood. In this case, > The oxygen molecules in the water helps out the fire, and we all > know how much fire needs oxygen. The hydrogen molecule also > doesn't hurt any. > > Does this clear things up? > -- > > Eric Lundblad You're right. Next time I''m having trouble getting a fire going, I'll just dump a bunch of Hydrogen and Oxygen (water) onto it and watch it take off. I'll also be more careful when lighting fires close to lakes and streams, lest they flare up.
ajf@pyuxa.UUCP (A Figura) (05/24/85)
> No really, the hot-cold water effect is true. The > principal that causes this also causes other things. For > instance, wet wood burns better that dry wood. In this case, > The oxygen molecules in the water helps out the fire, and we all > know how much fire needs oxygen. The hydrogen molecule also > doesn't hurt any. # # ##### # # # # # ## ##### # # # # # # # # # # # # # # ###### # # # ### # # # # # ###### # # # # # # # # # # ## ## # # # # # # I didn't see any smiley faces, but I must assume this was posted tongue in cheek. You can't seriously expect anyone who had an elementary chemistry or thermodynamics course to believe this? How are the oxygen "molecules" going to get disassociated from the hydrogen "molecules", so that they could burn and recombine into H2O? For one thing, it takes a whole lot more energy to split 2 H2O into 2 H2 + O2 than is released when H20 is formed. By your logic, every fire department in the world must be personned by arsonists; after all, they pour water on the fire - and everybody knows what a great fire-catalyst water is!!! By the way :-) Al "why did I waste my time getting involved with this BS" Figura @ Bellcore
thoth@tellab3.UUCP (Marcus Hall) (05/30/85)
>The rate at which a liquid approaches temperature equilibrium with >it's environment is related to the difference in temperature between >the liquid and it's environment. > ... >So, hot water cools ~faster~ than an equal volume of cold water >because the temperature difference between it and it's environment >is greater. Yes, but when the hot water reaches the temperature that the cold water was when it was put in, the ex-hot water cools at the same rate as the cold water did, but by now the cold water is even colder. The hot water may cool faster, but it has farther to go! >"But... But... wait!", you exclaim. "There exists a point at which >the ~hot~ water will be the same temperature as the cold! After that >point the temperature difference will be equal and they should cool >at the same rate." The point at which the temperatures are equal is when the ex-hot water freezes and reaches the same temperature as the cold ex-(liquid)water. >Yes, but the volume of the hot water will be ~less~ because some of >the hot water will have evaporated by that time. Since there is less >water to freeze, it freezes faster. So start out with less cold water in the first place! Really, is this serious? marcus hall
gino@sdchema.UUCP (Eugene G. Youngerman) (05/30/85)
In article <406@rtech.ARPA> eric@rtech.ARPA (Eric Lundblad) writes: > > No really, the hot-cold water effect is true. The >principal that causes this also causes other things. For >instance, wet wood burns better that dry wood. In this case, >The oxygen molecules in the water helps out the fire, and we all >know how much fire needs oxygen. The hydrogen molecule also >doesn't hurt any. > > Does this clear things up? >-- > > Eric Lundblad I have been following this whole argument with amusement. Some of it sort of makes sense -- especially the part about warm water evaporating, and then freezing faster because there is less of it. I havve trouble belieing a lot of the stuff about dissolved gases, but who knows?? Anyway, (No offense, Eric) water may or may not help wood burn, and wet wood may burn better than dry wood, but not for the reasons posted. Water (H2O) is a molecule. If you burn anything flammable that contains a hydrogen atom, you get water as a product. Burning is the act of combining (with the release of energy) some flammable or combustible material with oxygen. In the case of compounds containing only carbon and hydrogen, the most stable proucts are CO2 and H2O. Water in wood does not burn, the oxygen atom in water is not consumed. I hope that I have not added more fuel to the fire. Or perhaps I have fanned the flames. Or stirred the pot to boiling? Sorry GINO
rdp@teddy.UUCP (07/29/85)
Well, after seeing all the flames about which freezes faster, cold or
hot water, I think I will throw in my two cents worth, backed up by a
carefully orchestrated experiment.
When I was in high school, the assertion was made that hot water freezes
faster than cold. As this was completely counter-intuitive, we decided
to perfrom an experiment to prove this incorrect.
We took two otherwise identical ice-cube trays made out of aluminum, filled
one with cold tap water (about 48 F) and the other with hot tap water
(about 125 F) and put them next to each other in a freezer. Fully expecting
the cold to freeze faster, we were amazed that the hot DID freeze sooner!
WOW!
From there, we decided to win the Nobel prize in why hot freezes faster
than cold.
We tried different kinds of trays, different configuration, made sure
we use distilled water for all experiments, etc.
We did discover the following:
o When the trays are isolated from the walls or floor of the freezer
(by a block of styrofoam) the hot water seems toi freeze even faster
(relatively speaking) than if it was in direct contact (That shot our
theory that the hot tray melts into the ice, making better thermal
contact, which was a crock anyway since we were using a frost-free
unit).
o When the atmosphere was very very humid, the difference was almost
nil, sometimes with the cold beating the hot to freezing.
o tall and narrow containers favor the cold frezzing first, flat and
wide containers favor the hot freezing first.
Many experiments were done (taking nearly 6 months of time!) and it wasn't
until the end of things that a remarkable (to us) discovery was made. Some-
body decided to weigh the ice cubes that resulted. In ALL cases where the
hot water froze sooner, the ice cubes weighed FAR less, sometime as little
as a third the weight of those formed from cold water! What happened?
Well, the hot water sat there, and got rid of the vast majority of excess
heat, not through convection or radiation or conduction, but by EVAPORATION!
So the temperature very quickly dropped to the same as the water in the cold
tray, BUT, by that point, there was much less water left to freeze in the hot
tray, so all things being equal, the lesser amount of water froze faster.
This was confirmed by trying to freeze hot and cold water in otherwise
identical sealed containers. As expected, the hot water took forever to freeze.
Yes, it is really true, in the environment of many freezers, hot water can
freeze faster than cold, in normal, shallow ice cube trays, and sometimes,
the hotter the water, the faster it freezes (due to greater loss of material)
BUT the freezer is going to work a bit harder (because when that vapor
refreezes on the cooling coils, it's going to have to release all that
energy it absorbed evaporating)
However, rest assured that hot water DOES boil sooner than cold water.