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 Message Boards » » question about freezing temp/32 deg. at sea level Page [1]  
joerrad
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ok i have a strange question.

if water freezes at 32 degrees (@ sea level), what temp does water freeze at when it is above sea level or below sea level.

[Edited on December 27, 2005 at 10:06 PM. Reason : .]

12/27/2005 10:06:20 PM

9one9
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ahahahah

12/27/2005 10:06:51 PM

LiusClues
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ahahahah

12/27/2005 10:08:21 PM

AttackLax
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above = -13 degrees
below = 57 degrees

12/27/2005 10:09:39 PM

2
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ahahahah

12/27/2005 10:09:56 PM

CharlieEFH
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12/27/2005 10:27:56 PM

stowaway
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ahahahahahahahahahaha







http://www.csgnetwork.com/h2ofreezecalc.html

figure out the normal pressure at different altitudes and plug it in.

12/27/2005 10:31:34 PM

CharlieEFH
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12/27/2005 10:32:39 PM

2
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^^umm ocean water doesn't freeze at the same temperature as regular water

12/27/2005 10:47:47 PM

stowaway
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you change the salinity to 0

12/27/2005 11:03:05 PM

Duff Man
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i think water freezes at 32 degrees. for every 1000 feet in altitude you go up, you lose 4 degree on average.

i know that when we are preparing to go flying, we have to watch the freezing layer, based on what the temp where the first signs of visible moisture (clouds) is.

this is just from my standpoint, could be completely wrong.

12/27/2005 11:03:19 PM

moron
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This chart explains it more clearly, I think.

[Edited on December 28, 2005 at 12:18 AM. Reason : ]

12/28/2005 12:17:45 AM

JH Price
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^ how does this answer the question?

12/28/2005 12:31:45 AM

CharlieEFH
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stick to computers buddy

12/28/2005 12:50:55 AM

JonHGuth
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i fail to see how that explains it more clearly than a temp-pressure diagram

12/28/2005 12:57:35 AM

Duff Man
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alot of meterolgical terms are based on standard day, which is sea level 29.92 barometric pressure.

12/28/2005 12:59:21 AM

schmitter5
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Lowest Point in the World (and Asia)
Dead Sea shore, Israel-Jordan: 1312 feet / 400 meters below sea level
(The pressure of the atmosphere here is known to be extremely high, enough to filter the sun's UV rays.)

Lowest Point in Africa
Lake Assal, Djibouti: 512 feet / 156 meters below sea level

Lowest Point in Australia
Lake Eyre: 52 feet / 12 meters below sea level

Lowest Point in Europe
Caspian Sea shore, Russia-Iran-Turkmenistan, Azerbaijan: 92 feet / 28 meters below sea level

Lowest Point in Western Europe
Tie! Lemmefjord, Denmark and Prins Alexander Polder, Netherlands: 23 feet / 7 meters below sea level

Lowest Point in North America
Death Valley, California: 282 feet / 86 meters below sea level

Lowest Point in South America
Bahia Blanca, Argentina: 138 feet / 42 meters below sea level


According to Wikipedia though the actual lowest point is:
The Bentley Subglacial Trench is a vast trench in Antarctica. At 2,538 meters below sea level, it is the lowest point on the surface of the earth not covered by ocean, although it is covered by ice. It is similar in size to the nation of Mexico.

The trench is named after Charles Bentley, a geophysicist who led many scientific expeditions in Antarctica.

12/28/2005 2:11:38 AM

moron
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^^^ I read the original question improperly is how.

12/28/2005 2:17:58 AM

goFigure
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I CAN"T TAKE THE PRESSURE

PVT... but I took chem 101 5 1/2 years ago so I don't remember shit

12/28/2005 2:25:59 AM

humandrive
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For all practical purposes, there is no change in the freezing point of water with a change in elevation. It's not at all like the boiling point.

12/28/2005 7:21:59 AM

Maverick
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Quote :
"i think water freezes at 32 degrees. for every 1000 feet in altitude you go up, you lose 4 degree on average.

i know that when we are preparing to go flying, we have to watch the freezing layer, based on what the temp where the first signs of visible moisture (clouds) is.

this is just from my standpoint, could be completely wrong.

"


To expand, Clay is referring to the standard standard lapse rate (Average decrease in temperature of approximately 2C or about 5F per 1000 ft). The freezing temperature should remain relatively constant.

So in practical terms, if the temperature at ground level is 10C, then you can expect ice at 5000 ft.

The freezing point will not change, however, the average temperature will, which will cause icing at higher altitudes.


[Edited on December 28, 2005 at 8:10 AM. Reason : .]

12/28/2005 8:04:22 AM

Arab13
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lol that was a good one....

12/28/2005 4:27:16 PM

darkone
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http://www.lsbu.ac.uk/water/phase.html

12/28/2005 10:22:53 PM

EhSteve
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According to my thermodynamics textbook and the first problem we had to do last semester (this is the prof's solution, so if you think it's wrong, take it up with him):

5.10
a. The heat of fusion for the ice-water phase transition is 335 kJ/kg at 0 degrees C and 1 bar. The density of water is 1000 kg/m^3 at these conditions, and that of ice is 915 kg/m^3. Develop an expression for the change of the melting temperature of ice with pressure.

b. The heat of vaporization for the steam-water phase transition is 2255 kJ/kg at 100 degrees C and 1 bar. Develop an expression for the change in boiling temperature of water with pressure.

c. Compute the freezing and boiling points of water in Denver, Colorado, where the mean atmospheric pressure is 84.6 kPa.

a) along the coexistence curve:

(?P/?T) = H/TV => dP/dlnT = H/V

=> dP/dlnT = H/V = [H(liquid) - H(solid)]/[V(liquid) - V(solid)] = [335,000 J/kg]/[1000^-1 - 915^-1 m^3/kg]

= -3.61x10^9 J/m^3 = -3.61x10^9 Pa

=> P2 = P1 - 3.61x10^9 ln(T2/T1) Pa

or

T2 = T1exp(-(P2-P1)/(3.61x10^9 Pa)

b)

dP/dT = H/TV ~ H/TV(vapor) V(vapor) >> V(liquid)
~ PH/RT^2 => V(vapor) = RT/P

dlnP/dT = H/RT^2 , now, assuming H is essentially constant

ln P2/P1 = - [H/R]*[1/T2 - 1/T1]

or T2 = [1/T1 - (R/H)*ln(P2/P1)]^-1 = [1/T1 - (8.314 J/molK)/(2,255,000 J/kg)*(1000 mol/kg-mol)/(18 kg/kg-mol)*ln(P2/P1)]^-1

c) if the pressure in Denver is 84.6 kPa:

T2(freezing) = 273.15exp[-(84,600-100,000)/(3.61x10^9)]
=~ 273.15 = T1(freezing) essentially no change

T2(boiling) = [(1/373.15) - ((8.314)(1000))/((2.255x10^6)(18))*ln(84.6/100)]^-1

=~ 368.44 K = 95.29 degrees C



[Edited on December 29, 2005 at 5:19 AM. Reason : Note: the question marks should be deltas]

12/29/2005 5:11:14 AM

drunknloaded
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honestly without getting any formal education that asked this exact question

everyone know water boils in colorado at like 205 degrees or some shit and everyone knows that boiling temp they always say in text books is like 212 so if it boils at a colder temperature i would guess it freezes 7 or so degrees after 32 so my guess is 39

someone pm me with the right answer so i know if i should stay at state or not

12/29/2005 5:46:47 AM

EhSteve
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The freezing point doesn't change much with pressure.

That's why you get that nearly vertical line between liquid and solid on the P vs. T diagram.

12/29/2005 5:58:43 AM

jakis
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12/29/2005 1:46:56 PM

24carat
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EhSteve is correct.

But, even without any math, you can see it quite easily in the first graph darkone posted. I put in some hints for you below (with apologies to the many of you who don't need any help with it.)

Look at the chart and find the solid, liquid, and vapor phases.
The small "E" on the graph marks normal conditions at room temperature at sea level.
The melting/freezing point line is the black line between the solid and liquid phases just to the left of the little "E." Do you see the large section that is almost exactly vertical? That shows that with large changes in pressure (which is the same as large changes in altitude), the temperature of the phase change is the same. In other words, the Temperature value on that black line is the same (~273.15 K) regardless of whether the pressure is 1 kiloPascals or 10 megaPascals. Can you find the points on the line and convince yourself of that?

Now look at the line between liquid and vapor. It is not vertical and indicates that, as pressure drops even slightly (which it does as you increase altitude), the temperature also drops. The lower atmospheric pressure is why water boils at lower temp in Denver, and also the reason for high altitude directions for things like cake mixes.

12/29/2005 2:39:03 PM

humandrive
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Again

Quote :
"For all practical purposes, there is no change in the freezing point of water with a change in elevation. "


There, this is over and done with.

12/29/2005 6:30:01 PM

HockeyRoman
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And be glad that is the case or else it may not ever rain.

12/30/2005 6:22:02 AM

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