Freezing Definition and 161 Threads

Why do we define the freezing point of pure water as 0°C when most pure water does not freeze at that temperature? Instead, it can and does remain in the liquid phase down to temperatures as low as -48°C [Molinaro & Moore, 2011]. Cold-weather clouds throughout the Earth’s atmosphere...

Homework Statement The aqueous solution with the lowest freezing point of the following group is: 1) 0.01m MgSO4 2) 0.01m NaCl 3) 0.01m CH3CH2OH 4) 0.008m MgCl2 5) all equal Homework Equations Solutions have lower freezing points and higher boiling points than their solvents...

Homework Statement Calculate new freezing point and boiling point when 0.47 mol ethylene glycol and 0.14 mol KBr is added to 150g H2O. Express your answer using one decimal place.Homework Equations molality = moles solute/kg solvent ΔTf=i*Kf*m ΔTb=i*Kb*m New bp = ΔTb + normal bp New fp =...

After about 10 minutes of not moving the mouse or typing, my screensaver comes on, and the colors are kinda messed up and the computer freezes. I tried just disabling the screensaver, but whenever I go to the thing that let's me disable the screensaver, the screensaver comes up on a little...

Any idea what's going on here: http://www.sootoday.com/content/news/full_story.asp?StoryNumber=50683%20 Thanks...

I'm in a bit of a time crunch for science fair, and there are still a few questions about my experiment that are unanswered. What I'm dong is trying to accelerate the freezing of salt water by adding electrodes to the bottom of my container (attached to a battery). If the ions of the salt are...

I am trying to ascertain if a 150NB Stainless Steel pipe lagged with 50mm thick insulation would also require to be trace heated. The insulation used is rockwool. The parameters are that the pipe must not freeze solid given 5 straight days of -15 C with static flow. Wind chill is negligible. The...

Entropy of molten lead "freezing" Lead melts at 327.5 C.° The latent heat of melting of lead is 24.1 J/g, and the heat capacity of solid lead is 0.14 J/g °C. You take 100 grams of molten lead at a temperature of 327.5 C° and pour it on the sidewalk. The lead freezes and then comes into thermal...

Homework Statement Freezing Lake A small pond has a layer of ice 1cm thick floating on its surface. The air temperature is -10°C. Steps (a-c) should help you find the final answers in (d) and (e). (a) What is the temperature of the liquid water just below the ice? (b) Write the...

Homework Statement A situation is given whereby a thermometer is placed inside acetone of 80C and is taken out. A layer of ice forms around the surface of the thermometer, does the reading of the thermometer change? Homework Equations - The Attempt at a Solution At first I...

I have questions to a classic experiment : you have 2 equal containers filled with water. IN one the temperature of the water is 98° Celsius, in the other the water has 25° Celsius. If you put both in the freezer the one with the hotter water freezes first. Now i do understand that one looses...

Homework Statement Find the freezing point of water at the bottom of the ocean where the pressure is 32.52bar Homework Equations Clausius-Clapeyron equation in the form of: ln(p2/p1) = deltaHfusion/R * ((1/t2)-(1/t1)) Where the deltaHfusion is 6.008*10^3 J/mol where the...

Sorry if this is an obvious question...I understand how the justification via the pressure v temp graph works, but I'm not quite understanding freezing point depression in terms of intermolecular forces and temperature. I was taught that due to attractive IMF between solute and solvent particles...

Homework Statement I think this is the right formula: ΔTF = KF × b × i Freezing-point depression. I have the amount of salt added to the water but how am I going to do to calculate the difference in temperature? Or with other words the freezing point of water saturated with salt (NaCl)? Or...

Hi all, I just need a little clarification here, please. I'm a tutor and I've been helping a student with their freezing point depression lab and the student has to determine the molar mass of an unknown solute from the experimental data provided. I understand the process and have been...

Hi, As I understand, by placing water in a vacuum and decreasing pressure, vapor pressure will subsequently be increased causing the water to boil. The water will then evaporate, which will cool the water that is left behind. Further evaporation over a period of time will drop the water...

Homework Statement Explain why the temperature gradually drops as the solution is in the process of freezing? Homework Equations None The Attempt at a Solution No idea how to start!

Hi all, I am having trouble grasping the phenomenon on why the LPG tank freezes as you use up more and more of the gas inside. My understanding is this. Initially, the tank is full of liquefied gas, and as you use up the gas, the pressure inside the tank drops, and since the temperature...

I recently came across an odd phenomenon known as Mpemba effect. It says that hot water freezes quicker than cool water provided that temperature difference is not too much. E.g. it can be, say, 30 degrees Celsius and 50 degrees Celsius but not something like 99 and 1. Unfortunately, the book...

Is it correct to say that a water droplet on a surface freezes by heat transfer from the droplet through the water-substrate interface, and a subsequent nucleation process whereby minute particles on the surface (or the surface roughness) acts as nucleation centers? Do you know of a...

"For a pure substance, melting occurs at the same temperature as freezing." Does it means that if impurities are added, then the melting point of the substance is not at the same temperature as freezing ? If yes, how you would explain this ?

How fast do i need to pump water in a 10" aluminum pipe to prevent freezing? Assume 32*F inlet temp and 0*F ambient . For my conditions, the temps will vary and T ambient easily gets down to -20*F or more.

Hi, Does anyone have a formula for the freezing time (ie time taken for it to freeze) of a fixed volume of water (1mL) at a given temperature (Ts) and pressure (1 Atmosphere) when the surrounding temperature is set to below 0 Celsius (Ta < 0C) ? ie. I'm looking for Time to freeze if you...

Is it possible to freeze liquid in tank with compressed nitrogen? Tank has double sides where nitrogen is relased. Also there are numerous nozzles inside tank through which nitrogen spray. Would be final result solid form of liquid? What is difference in time, amount of nitrogen needed for 50...

Homework Statement The enthalpy of fusion of mercury is 2.292kJ/mol and its normal freezing point s 234.3K with a change in molar volume of +0.517cm^3 /mol on melting. At what temperature will the bottom of a column of mercury (density 13.6 g/cm^3) of height 10.0m be expected to freeze...

New computer constantly freezing?? Hey guys, I have a problem here. I recently bought a brand new computer with Windows 7 Home Premium on it. It has an AMD Athlon dual core 2.0 ghz processor, and the computer initially came with 2 gigs of DDR-2 RAM. Now, when I got the computer, I threw in...

Dear all, I am reading some texts about quintessence. As you one of the best textbooks for cosmology is Weinberg's. in page 90 of his book he states that if we consider astronomical units we can see that a good quintessence potential is V(\phi)= (M^(4+alpha)) * phi ^(-alpha) and M has...

When I first turn on my computer in the morning, it will have intermittent freezing problems when I'm trying to do stuff. Like if I come here and click on something, it will freeze for a few seconds, but my cursor can still move, but it's just slow. After everything I do, it will stop, take a...

Homework Statement Wine that is 28.4% ethanol by wt is set outside. Will it freeze if the temp drops to -10 C? (assume water is the solvent) Homework Equations \DeltaTfp = kfp*molality of solute The Attempt at a Solution 2.84 g of ethanol/10 g total =.284 mole \DeltaTfp= -10 ?

I couldn't sleep last night and was watching some news special at 2 AM on "fat freezing", a new way to shed body fat. http://abcnews.go.com/Health/freezing-fat-fda-green-lights-weight-loss-treatment/story?id=11641994 I don't know if this is the same video, but it was wild! They took this...

The unusually cold weather in Europe must be related to the gulf stream which gives Europe its normally balmy temperatures as far north as the Arctic Circle in Norway. It was noticed this summer that the gulf stream had slowed down to almost a stop. Some scientists attributed this to the BP...

Homework Statement 200 g of ethylene glycol (HOCH2CH2OH) is dissolved in 1.00 L of water at 25°C. The cryoscopic constant of water is 1.86 °C molal-1. If the solution is chilled to -25°C, how much ice (in g) will be separated out? Homework Equations ΔT=Kfm, where Kf is and cryoscopic...

Could somebody please estimate the air temperature that water freezes at. During a recent very cold night I left an open plastic container of ~50ml of water next to an alcohol thermometer in an uninsulated garden shed. By morning the thermometer was reading minus 3 degrees Celcius but the...

Hey, I really need help in my chem homework. :( how many grams of ethyl alcohol CH2OHCH2OH must be added to 37.8g of water to give a freezing point of -.15 degrees C.

Homework Statement How do I write it in calculus notation? Delta T = i k m were Delta T = Change of temperature i = van't Hoff value m = concentration in molality k = molal freezing/boiling point constant for the solvent THANKS! Homework Equations The Attempt at a Solution

[b]1. When water vapor is condensing or liquid water is freezing? Homework Equations [b]3. The two are affected by the energy of the sorrounding environment is being absorbed into the water.

I've been pondering this question a while regarding how water freezes. Assuming the temperature above a lake is 0 degrees centigrade, the water at the top of the lake would decrease in temperature until 4 degrees centigrade at which point, being at its densest, would sink towards the bottom of...

Hi I was wondering if anyone could help me out with this question? You place 100ml of water into a freezer and monitor the variation of the temperature of the water with time. After some time you find that the temperature reaches 0ºC, then remains constant at 0ºC for a period of time before...

I am trying to develop a battery operated invention that will be used primarily in sub freezing conditions. From what I can tell from my research so far, a simple 9 volt NiMH or lithium will work fine under these conditions. The only problem I foresee though is that when this was eventually a...

Homework Statement A solution is made by dissolving 250.0 g of solid potassium chromate (K2CrO4) in 1.00 kg of water? what will be the freezing point of the new solution. Homework Equations [Delta]T(freezing point)=(Van't Hoff Factor)(molal concentration of solute particles)(molal...

I was wondering if someone could explain how ice crystals are being formed in the tank/pipeline BP is trying to use to stem the flood of oil pumping into the ocean. A friend and me were discussing it and a few questions came to mind about it, not just related to this issue. He suggested that...

in chem. class asked the question nd he ignored me, i hope smeone here can help me? wht are the properties of electrolytes nd how do yu kno they coduct electcity nd also how ud yu determinet lowest freezing eezing poin

please is there a topic that discuss with illustration factor that causes Strange behavior of the density of the water around the freezing point

A technician freezes some ethanol by removing 9.53x10^4 J of heat energy from it at its melting point. What mass of the ethanol is she freezing?

Hello, this is my first post :) I will be very glad if you would answer my question. Does freezing point decrease if water is flowing or in otjer words,"does flowing water freeze more easily than still water". if the answer is yes, would you please give me the link of the source or paper. iwill...

Im doing my chemistry lab and ran into trouble with this problem. I am not even where to start or what formulas to use. Any ideas? Thanks. Suppose that a student calculated Kf of biphenyl to be 81.2 C kg/mol. Calculate the molar mass of an unknown if a solution containing 1.64g of an...

i fill two ice trays, one covered and one not. The ice in the covered tray freezes the ice to the point that the ice is much more difficult to extract from the tray. Why is that?

I don't know what the weather has been around the nation and world this week, but here in the great NW we have been freezing our buns off! All week we [at our house] were at or below 10 degrees F at night, with daytime highs well below freezing. Today we finally hit 33 degrees with freezing rain...

Homework Statement Hi, I have a problem with the data and calculations part in my lab. For some reason, I can't get a molar mass of the given solutes to match my answer. I'll provide all the equations and my numbers. Please I really need help with this Homework Equations deltaT = m(kf)...

Homework Statement Find the molar mass of a nonpolar molecular compound if 5.52 grams dissolved in 36.0 grams of benzene begins to freeze at -1.87 C? The freezing point of pure benzene is 5.50 C. The freezing point depression constant is -5.12. Homework Equations (Change of...