First, let me thank you all for your responses. (I have
        made them ALL anonymous)
 
        Second, if you do not have a half hour, don't start to
        read this.
 
        Third, if you do read this, I think you'll find that the
        debate has a LONG way to go before it's over.
 
        Enjoy...Karl
 
 
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I would guess that they use hot water because:
 
1. It doesn't freeze up while *in* the Zamboni.
 
2. It melts the chipped, snowy surface somewhat making for a stronger
   sheet of ice.
 ============================================================================
HOt water freezes faster...learned that in 10th grade biology, but it's
also what causes ice crystal build up in the freezer...
 ============================================================================
        If I remember correctly (from MR. Wizard), hot water freezes faster
because the monecules of warmer water are more active (have greater
energy) than colder water.  This allows hot water to lose it's heat
faster (ie: get colder) through giving off water vapor.  Now, I don't
know if there's some point of diminishing returns or not, but I "tested"
this idea one time.  I put 2 ice cube trays in the freezer-one w/ hot
water, and one w/ cold.  I periodically check on them and the hot one
froze first.
 
        Maybe you'll get a more scientific reply.  If not, I hope
this was good enough.
 =============================================================================
That's an old wive's tale. Hot water obviously first has to cool down to the
temperature of cold water and then do whatever the cold water does to freeze.
There can sometimes be small differences in the rate of cooling, just because
hot water has a somewhat different percentage of dissolved impurities than
does cold water, but water at 40 degrees, say, is going to turn into ice much
sooner than water at 100 degrees.
 
I think the real reason that Zambonis use hot water is that the ice gets
scraped up, both by players' skates and by the Zamboni's scraper. If you dump
hot water on this scraped-up snowy stuff, the hot water will melt it and it
will all refreeze into a nice solid sheet of ice. If you dump cold water on
it, however, the snowy stuff won't melt completely and the mixture of snowy
stuff and cold water will refreeze into slushy ice with a lot of trapped air
inside it, which makes for really lousy skating.
 
Hope this helps...
 ============================================================================
I've heard that hot water freezes faster, because there will be less of
it to freeze.  In other words, the "steam" you see off of hot water is
water vapor, meaning that there is less actual "water" (liquid) to
freeze.  Hot water has more vapor than cold, therefore, will freeze
faster.  I read that somewhere.
 ===========================================================================
Karl,
 
I've heard the argument several times as to why hot water is supposed to
freeze faster than cold, but I've never been convinced. Maybe there's a
mental block in there someplace, because I also can't remeber exactly why
it's supposed to be true.
 
I think it has to do with the fact that the temperature differential between
hot water and ice is greater than between cold water and ice, therefore heat
(in calories) will flow faster from the water to the ice, thus reducing its
temperature faster.
 
But, I believe that there are more calories to be extracted from hot water.
It takes the same amount in either case to turn 32 deg. water to 32 deg. ice,
but it takes ADDITIONAL calories to turn (hot) water to 32 deg. water, and
it's only during this part of the change that the extra temperature difference
is effective. In other words, FIRST you have to cool the water to 32 degrees,
THEN you have the identical task of actually freezing it. Therefore, I have
never believed the claim.
 
If you hear of a better explanation, I'd love to hear it.
 
I would think they use hot water so that the rough ice surface is melted
slightly before refreezing, thus levelling it better. If you applied cold
water it might freeze too quickly in the "valleys", leaving the rough ridges
sticking through. That's just my opinion, though...
 =============================================================================
Karl,
 
Not only does the hot water freeze faster (it has less surface area than
cold water), but it bonds to the ice below it.
 ===========================================================================
        Karl, cold water freezes quicker.  To illustrate, set two
glasses of water outside on a cold day (assuming it gets below freezing).
Let one glass be room-temperature tap water and let one glass be very
hot water.  Actually, don't use real glass because the hot glass may
shatter - use plastic cups.  Anyway, assuming each cup holds the same
amount of water and both cups are of the same material, the one with
the colder water to start will freeze first.
 
        By the way, the mechanical engineer in me (Wow! I actually
get to use this stuff...) says that hot water is put in the Zamboni to
better melt the top layer of ice.  That way, it's easier to get rid
of all the blemishes in the ice surface.  I would bet the Zamboni guy
just tossed out an answer.  Anyone in the "cyber-rink" out there
have an opinion?
 ===========================================================================
Dear Karl,
I got a kick out of your post on the hockey list about which freezes
faster hot or cold water. I live in Fairbanks Alaska and work at the
University of Alaska Fairbanks. Fairbanks is a hockey town and the
subject of ice is often in our conversations around here, since we have
ice and snow between 7 - 8 months of the year.
 
Hot water freezes faster due to the smaller amount of oxygen in the water
than cold thus allowing the water to freeze just a little faster.
 
We have a rink in our yard each year for my kids to play hockey on and
many of the kids from my sons team come and play also. Our rink is one
fourth the size of a sheet that they usually play on. Making our rink 100
feet by 40 feet. It is a blast to play on, we keep it resurfaced several
times a week and have lights and boards also. The best part of the rink
is that we can skate from October to April on it. This year we have used
cold water and sprayed the surface while in other years we hot mopped the
surface. To our surprise the sprayed surface is great and even better
than any of the dozen or so outdoor rinks in Fairbanks, even the one with
a Zam keeping the ice.
 
Fairbanks is a great town for playing and following hockey just a little
out of the way. This year the UAF Nanooks are suffering through a
rebuilding season. Last year we delighted in having the top two scorers
in Div. I, Fedorchuk and McMillian. Not this year we will have to wait
till next season I guess. But the town still supports the team with about
3,600 folks a game and sellouts reaching 5,000.
 ===========================================================================
     karl,
 
     i'm no scientist, but i would think hot water takes longer to
     freeze.  my guess is that you agree; hence the question.  the
     time spent freezing should be proportional to the units of heat
     required to be removed from the water in the freezing process.
     on a much more basic level, if i were to put one ice tray in the
     freezer with hot water and one with cold water, i'm sure the one
     with cold water will freeze first.
 
     i think the benefit from the hot water is that it will definitely
     make the ice surface smoother.
 
     i was always under the impression that the zambonis used a
     special chemical which freezes *quickly*, not just plain water.
     then again, i've never operated a zamboni.
 
     if you could, let me know what the answer is (when you find out,
     of course).  if nothing else, i will get quicker ice cubes in the
     kitchen.  :-)
 ============================================================================
Karl,
        There's two reasons, one you have less free oxygen molecules.  In other
words water is always H20 (2 hydrogen molecules and one oxygen molecule
combined) no matter what the state steam, liquid, or ice.  However there can be
extra oxygen in the water.. this is what fish extract in there gill's.  Anyway
highly oxygenated water freezes slower.  Remove the free oxygen and it freezes
faster.  When water is heated the extra oxygen escapes into the air.  The other
reason deals with the adgitation of the molecule.  When water is heated the
molecules are vibrating faster and bouncing around, when water is frozen the
molecules are just vibrating rapidly.  In water that's at say room temp the
molecules move real slow and don't vibrate.  Chem 101... that's about how I
recall, but then I'm an engineer not a chemist.  If you would like to prove that
hot water freezes faster, you can fill an ice tray with hot water and one with
cold water place both in the freezer and check every 10 to 15 mins.  I should
also point out that it's free oxygen that's removed in heating not the oxygen
attached to the water molecule, or you would not have water only hydrogen gas.
If you extracted one hydogen atam then you would have the very unstable HO
(hydrogen per oxide) gargle gargle.  This is way HO comes in a dark bottle and
states alway replace the cap... if you don't you end up with water... free
oxygen from the air enters the bottle.
        I always tell the kids and wife to make sure to use hot water when
filling the ice tray.  I also scold my wife if she places vegetables in cold
water and puts them on the stove to boil.  Most people think if hot water
freezes fast then cold then cold water should boil faster then hot... not the
case.  But that not my point on the vegies the vitamins and other good stuff
leaches out into the water and you loss most of the goodness... unless you
drink up the left over water and even then a lot of good things for you are lost
in the air.  However if you place the vegatables in boiling water it blanches
the skin sealing in all that good stuff... beside who would what to eat a potato
with out all the good stuff... it would only be starch.
        For my wife's part she tells all her friends never marry anyone with a
science type degree.  Well this was more then you asked for...  Let me know if
you get anyother reasons then what I listed... should be interesting.
 =============================================================================
According to my scientist husband, hot water will freeze faster because it cools
at a faster rate than cold water...I don't quite believe it, but that's what he
says!
 ===========================================================================
Which freezes faster hot or cold water ...
 
For equal mass --  cold
 
This is going back a bit in education but I'll give you
what I remember having to compute.
 
Hot water has a higher heat transfer coefficient and
will change temperature faster than cold water however
there is a loss of liquid mass (to vapor) so that
when the water reaches the same temperature as the cold
water there is less to cool to freezing.
 
Under the right circumstances (high surface area like a
hockey rink) the amount of mass loss could be sufficient
so that it seems that hot water freezes faster than cold
water.
 
Make sense ...  I'm sure if I had any college notes I
could look up the exact equations if needed.
 ===========================================================================
I'll give you a trick answer.  Hot water doesn't freeze, so it must
be cold water, but since hot water becomes cold water before freezing,
neither freezes faster.  If you meant "which will freeze first,"
I will conjecture cold water.
 
These are the types of experiments performed on a daily basis by
scientists stationed in Antarctica and Army Engineers in Greenland
(I'm not making this up) using technology that the average person is
ill equipped to contend with, such as Dixie cups and Evian.  The
request for such experiments came out of inconclusive research in the
quest for the perfect popsicle.  The hot water popsiclists believe
that the pigmentation and flavor additives to the popsicle base
(water) dissolve better in hot water.  This can be confirmed by asking
anyone who makes Jell-O molds for church banquets on a regular basis.
The cold water camp, on the other hand, is primarily concerned with
rapid popsicle turnover and insist that incompletely dissolved
coloring and flavoring will dissolve adequately when melted in the
mouth.  As children, cold water popsiclists could often be found
with their tongues stuck to flag poles.
 
The specific heat of a substance is number of calories of energy it
takes to raise the temperature of one gram that substance in its
current phase (solid, liquid, gas) by one degree centigrade.  For
example, the specific heat of water is 1.  Although I don't know the
exact numbers, the specific heat of iron is less than 1 (0.01 or
something like that), and the specific heat of vinyl is more than 1
(10 or something like that).  I think the specific heat of air is
sort of the same as the specific heat of water.
 
Before water can freeze, it has to be at a temperature of 0 degrees
centigrade.  The surrounding air is capable of absorbing heat energy
from water at a constant rate, since the specific heat of both water
and air is constant, it is obvious that the cold water will reach 0
degrees before the hot water will.
 
In order to freeze (become ice at 0 degrees Centigrade), the
surrounding air must absorb much more energy from the water than was
required to cool it to water at 0 degrees centigrade.  This is
accomplished by means of a special tax called the coefficient of
freezing.  So while the cold water is paying a freezing tax, the
hot water is still cooling down to the point where it must begin paying
its tax.  While I haven't performed this experiment yet (still watching
paint dry), I would assume both would turn to ice pretty close to the
same time.  This coefficient of freezing works the same way when heating
ice to become water at 10 degrees centigrade or 50 degrees centigrade.
Most of the energy goes to melting the ice to become water at 0 degrees.
 
To perform this experiment, contact the Ice and Water Administration of
the Department of Energy, and request document IW-93-596(a).  This will
detail the experiment mentioned above, but equipment is used that can
be quite costly.  It may be duplicated in a less costly manner by suspending
a Dixie cup full of hot water and one full of cold water from separate
finch feeders (you may want to cover them with clear plastic--the
specific heat of finch poop is probably not 1) and leaving them outside.
Send the kids out to wait for them (the water cups) to freeze.  After
the water freezes, bring the kids inside and give them a hot water
popsicle.
 ===========================================================================
Actually, hot water DOES freeze faster. The reason is that the particles
in hot water are moving faster so that they radiate off more
heat and thus cool faster.
 ===========================================================================
Karl,
 
Several people I have posed the question to agree that hot water has to take
_longer_ to freeze. However, two interesting sidelights to the hot/cold ice
issue have surfaced -- my son pointed the first out to me (I had forwarded
to him a copy of my reply to you earlier). The second from a mechanical
engineer here at CRD.
 
1:
 
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:
: stuff deleted
:
     However, there is one major difference between freezing hot and cold
water.  Normally you put cold water in ice cube trays, right?  Imaging an
ice cube in your head... see how "cloudy" it is?  That's air bubbles
trapped, or frozen, in the ice.  The next time you make ice cubes, use
boiled water (full rolling boil - right into the trays).  When it is finally
completely frozen, you will discover that the ice is perfectly clear (no
bubbles).  This makes much harder ice, and therefore a much better surface
to skate on.
 
     Just a little scientific trivia applied to real life...
 
----- End Included Message -----
 
I doubt that the Zamboni has _boiled_ water, however...
 
2:
 
If you pour a cup of hot coffee which you won't get to drink for, let's say,
5 minutes, and want to add cold milk, when should you add the milk to have
the hottest coffee, now or just before you drink it?
 
The answer is -- now. It will cool the coffee to a lower temperature at the
start of the 5 minutes and the lower difference between the coffee and room
temperature will result in less heat loss to the air. If, OTOH, you leave
really hot coffee for 5 minutes, it will lose more heat, then the cold milk
will take it to a cooler final temperature.
 ============================================================================
As a former chemistry major, I assure you that cold water freezes faster than
hot water.  They fill the zamboni with hot water, not because it freezes
faster, but because they want to melt the immediate layer of ice below the
blades.  Otherwise, they would end up with a brittle top layer.
 
The time it takes for water to reach the freezing point is not based on the
separation between the molecules (which is the argument the 'hot water faster'
 folks use.)  Try it sometime.  Put some hot water in a cup and an equal
amount of cold water in another cup and set them outside when it's below
freezing.  You will see the ice crystals forming in the cold cup before they
form in the hot.
 =============================================================================
I don't know which freezes faster.  But I always thought the reason
for using hot water in resurfacing was so the water put down would
bond with the ice rather than forming a thin sheet on top that would
flake off.
 ===========================================================================
As a maniac hockey player from my childhood days in Canada (the
country where ice was born, as one ad says), and as a Chemistry
professor, I can offer what I think is the answer to the "hot water
versus cold water ice" question.
 
Why do you you often get a big stream of fizz and bubbles when you
open a warm can of soda (beer) but not when the beverage is cold?
Gases are more soluble in cold water than in hot water.  When you
heat up water, dissolved gas tends to leave the solution as bubbles.
 
Water out of the tap has lots of oxygen and nitrogen dissolved in it.
(If it didn't, then fish couldn't "breathe" underwater.)  If you heat
up that water, the air tends to leave the water.  You can observe
gas leaving hot water if you heat up some water in a glass pan on
the top of the range.  Bubbles start to form long before the water is
hot enough to boil.
 
Gases can not remain in the water when it crystallizes... when it freezes.
So, if there is gas in the water, it forms bubbles in the ice.  Ice
with gas bubbles in it is "cheesy" ... it is soft and easily broken
into bits.  Ice without bubbles is much stronger and harder.
 
Therefore, for better ice, you want to make it from hot water (with
less gas in it).
 
You also might want to use hot water for the following other
reasons:
a) To melt any ice shavings that the Zamboni did not pick up
b) To make sure that the new ice bonds well to the old ice beneath it.
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