7th Grade Science Project Underway - Freezing Moving Water

Eric Patterson

Eric Patterson

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Will moving water freeze? More specifically does moving water freeze at a lower temperature than still water. Here is Thomas's set up. He's got two beakers in the freezer, each with 300 ml of distilled water. One beaker, the control, is sitting still with a digital temperature probe in it. The second beaker is sitting on a mixing plate, and it has a second temperature probe. The mixing plate is a motorized magnetic plate and you drop a "pill" in the beaker which spins as a result of close proximity to the mixing plate, thus moving the water continuously. The distilled water started out at room temperature. Every 10 minutes he checks and records the two temperatures in a log book. He's 30 minutes into the experiment and the temperature is dropping similarly.

Care to predict what happens as the experiemt continues?
 
Sounds like a nice science project. When you see the non stirring control start to freeze you may want to move
the temperature probe to the one with the stir motor, due to the fact that the motor may be creating heat and keeping
the temperature slightly higher.
 
Will moving water freeze? More specifically does moving water freeze at a lower temperature than still water. Here is Thomas's set up. He's got two beakers in the freezer, each with 300 ml of distilled water. One beaker, the control, is sitting still with a digital temperature probe in it. The second beaker is sitting on a mixing plate, and it has a second temperature probe. The mixing plate is a motorized magnetic plate and you drop a "pill" in the beaker which spins as a result of close proximity to the mixing plate, thus moving the water continuously. The distilled water started out at room temperature. Every 10 minutes he checks and records the two temperatures in a log book. He's 30 minutes into the experiment and the temperature is dropping similarly.

Care to predict what happens as the experiemt continues?
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Too bad you aren't closer, I could have hooked you up.
 
Ever see pics of frrozed waterfalls? Moving water will freeze and it will freeze at the same temperature of still water. So what your experiment is trying to determine is rate of freezing. I'm curious why distilled water was chosen? Makes it a much more interesting experiment.

How cold is your freezer? Is there air movement when your freezer is moving? How fast is the stirrer running?

One significant factor is that water has its maximum density at 4 degrees C. In still water, the whole volume cools down to 4C as the colder water sinks to the bottom. A thin layer at the top surface can then quickly cool to 0 degrees C while floating on the denser water below, and start to freeze.

In moving water the whole volume has to cool to 0C before freezing starts.

The temperature rise generated by the energy needed for stirring is unlikely to be significant.

Great experiment. I'll be interested to hear of your Son's results and observations. A great follow on experiment would be to put the water into a metal beaker with many scratches on the inside.

Do update when you get a minute Eric.

Mark W
 
Still water should freeze at 32 degrees F. The moving water I would think will freeze at a lower temperature according to the speed of the water. Faster the water the lower the temp.........Then somebody has to walk around in the water so the ducks can have a place to land. LOL
 
Here is what happened. Note, both temperature probes were placed at the bottoms of the beakers.

Once in the freezer both beakers began cooling at apporiximately the same rate, fairly rapidly. The non-stirred beaker began icing up when it's probe read somewhere around 1.8 degres celsius. Skim ice formed on the surface as expected. Within the next ten minutes the stirred beaker began freezing as well. However, it did not form skim ice, rather it became slushy around the perimeter. For the next several hours the temperature hovered around 1.4 degrees celcius. The rapid decrease in water temperature we observed early-on stalled as the water was turning to ice. Ice continued to grow in both beakers. The un-stirred beaker's ice thickened from the top. The stirred beaker's ice thickened from the perimeter. At midnight we went to bed observing the temperature was still around 1.4 degrees celsius. Both beakers were over half frozen. The stirred beaker was frozen except for the area surrounding the stirrer. When I woke up this morning and checked the temp had fallen to -19 degrees and both beakers were frozen blocks. As somewhat expected it takes a lot of energy to change states so as the water was freezing the temperature changed little. Once frozen solid it dropped to the surrounding temperature.

From this we deduce that moving water will freeze, without a doubt. The stirring rate was rather brisk (tornado in water) yet it froze at a rate similar to the control unstirred beaker. If stirring water depresses the freezing point our test set-up was not accurate enough to detect it and the difference in freezing point would be very small.
 
Mark

Thomas used distilled water to remove impurities that affect the freezing point and from what he learned in researching the topic the way the ice can actually form. I measured the freezer temp and it holds a steady -19 degrees Celsius.
 
Tod

Hook us up? You mean lab facilities or equipment? We did this on the cheap ordering digital thermometers, beakers, and a brewer's stir plate from Ebay. Cost was around $40. Thanks.

Eric
 
Tod

Hook us up? You mean lab facilities or equipment? We did this on the cheap ordering digital thermometers, beakers, and a brewer's stir plate from Ebay. Cost was around $40. Thanks.

Eric
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.....and some yeast, hops and bottle topper.

Back on the subject, that is a neat experiment. I always enjoyed doing the science experiments with my dad.
 
Thanks for the follow up. Your results are what I would have predicted. Main reason is that you used distilled water, and your beakers were basically thermally isolated from any outside influences.

As your son learned from his research, impurities in normal tap water would have been soruces of crystalline growth (nucleation) which would have changed the outcome of your experiment. Good job Thomas on understanding this and taking this variable factor out of the experiment.

Isolating the beaker in the fridge removed the potential effect of air currents changing the rate of freezing. It also removed any other surrounding temperature variations that would have effected the outcome.

Nice job Thomas, hope you enjoyed the learnings.

Mark W
 
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That's a neat experiment and the results are what I had thought they would be. Watching water freeze, especially moving water is quite interesting.

One of the most unusual days was the last day of our season several years ago. Temps had been well below freezing for several days with the nights down to low teens. We hunted along the main channel in pool 8 of the Mississippi River - the only spot open. I had several long lines of 1/4" braided nylon with Toledo Magnum Golden Eye decoys attached with 30" droppers. That particular morning it was bright sunny but the temps were close to 10 degrees. As the morning progressed the decoys were gathering ice by the minute and eventually totally flipped upside down. That in itself was something that I hadn't seen before but what happened next really was interesting. The main lines themselves were gathering slush ice even though they were a couple of feet below the surface and eventually came right up to the surface due to the bouyancy of the ice on the lines. Very odd to have all the lines encased in slush ice. About that time we had had enough of the weather, had shot a few ducks including one of the most perfect Bull Cans I have ever shot and headed in.
 
Tod

Hook us up? You mean lab facilities or equipment? We did this on the cheap ordering digital thermometers, beakers, and a brewer's stir plate from Ebay. Cost was around $40. Thanks.

Eric
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Yes, on the above. $40 is a great price for those supplies.
 
I was pleased when I found the brewer's stir plates for half what a real lab supplier charged. For our purpose it worked great. Never know when it might get used again. I could drink iced tea from the beakers and use the stirrer to make it real sweet, just the way we like it in the deep south. Throw a hummingbird into a diabetic coma.
 
Eric, Thanks for posting. It brought back memories of Meg's 7th grade project, we messed with Archimedes pump design. Got her a 3rd over all and top 7th grader. Way fun! (at least for me ;^)

Scott
 
Scott

That reminds me of a project Andrew and I did. He had a history project and chose the 5 star generals from WWII, plus Patton. We did a big tri-fold board with all their pictures, some facts about each, their accomplishments, etc., and used the army stars to border it with the 5 star logo in each corner. Teacher said it had to be color but we used all black and white and it looked KILLER with the generals B&W pictures. It was one project I wanted to keep. Well the teacher liked it so she kept it as an example for future classes. Andrew suffered and worked hard on it and to this day knows more about the WWII generals than most adults.

How's the empty nest these days?

Eric
 
Eric,

Andrew is one smart cookie. The few conversations I had with him left me feeling like the class dunce. I imagine the time you two spent together on that project will be long remembered by both of you.

So did the teacher ding Andrew for no color? :>) :>)
 
Prediction:

Water at the same temperature will freeze if it is moving or not only dependent on the friction/heat caused by the turbulence to keep it from freezing solid. There will be a point where the turbulence of the water or friction causing heat that it will not be able to overcome the rise in thermal delta above freezing. If you reach this temperature the motor will burn the fuse because the bowl will be frozen solid. But those temperatures are dependent on the flow or turbulence. Can not be exact on the temperature but will assume below the 10 degree mark into the negatives depending on the velocity of the flow there will be no stopping a mass ice crystal from holding together. Once you reach this the show is over...Only the velocity of the spinning element in the bowl will be free.

You can probably have the thesis claim of there will be no direct correlation that will benefit the distilled water from any other water source except slight impurities that may change the freezing point of only a small percentage from the 32 degree mark. Dihydrogen MonoOxygen (joke) freezes at the same temperature.

His experiment will probably take a 24 hour period or longer if the freezer is slightly below the 32 mark but the mixer plate will never freeze solid due to flow and slightly elevated temperatures only around mixing plate.

Wonderful experiment.

Add a third bowl by adding boiling water with the mixing plate...You might be amazed! Or even ask your son, does cold water freeze faster than hot water?

Regards,
Kristan
 
sounds like a great experiment. glad thomas had some fun with it.

When I was working for Aldrich Chemical, (now Sigma Aldrich Chemical) we used to use HUGE spin bars about the size of cow magnets in 50+ liter beakers. Was a fun time, well until the maintence guy shut off the a/c and the lab blew up and part of I 94 in milw. Thanks for bringing back the memories of that one!!!

Eric, (and others) look up "Putt Putt boats" They make for a great experiment in the fairs, few people have ever done them, you can get pretty creative and world wide they even have competitions and such with them. Just fill a kiddie pool or a plastic sled and have some fun. My kids won 1st place with them.
 
Very interesting. So why do sections of a river remain open while most of the river is frozen? I always assumed this was because of a swifter current in these open water areas...
 
You have to look at the source of supply. Is it all surface water or are there springs feeding into it. Is some parts of the river deeper, narrow and faster moving. The experiment had cold effecting all sides of the container. Lakes and rivers are a top down freeze process. Also, rivers can have warmer water discharges from treatment plants or other sources.

I believe the experiment was to show that static water will freeze solid faster than water in motion until you reach very low temps. I do not want to cause Eric any extra expense however, to make all things equal the unit that was used to put the water in motion may have imparted some heat to the container because of it's operation. The static container should also have been set on the same unit and settings without the mixing instrument if this was timed test.
 
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