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Freezing Point

Science brain teasers require understanding of the physical or biological world and the laws that govern it.


Puzzle ID:#29350
Fun:*** (2.55)
Difficulty:* (1.09)
Submitted By:bigSWAFF_69_Aus******




The freezing point of pure water is 32 degrees Fahrenheit (0 degrees Celsius). However, by simply adding a common household ingredient, you then can easily cool the water 20 degrees past the freezing point, and still keep it in liquid form.

How is this possible?

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Mar 27, 2006

You can also raise the boiling point the same way. Good job, Swaffy!!
Mar 27, 2006

I've obviously learnred something at college!
Mar 27, 2006

Hence the science behind home-made ice cream! good job. Keep em coming.
Mar 27, 2006

you learn something new everyday =) nice one!
Mar 30, 2006

I thought is was ice.
Apr 02, 2006

i got it right! nice one..
Apr 06, 2006

yay i got it right!!!
Apr 21, 2006

You learn something new every day!!!!
Apr 23, 2006

It was very very very easy.
Apr 27, 2006

you do not have to only add salt...any chemical will do...this works because it decreases the attraction between the water molecules by acting as "spacers" between the water molecules. When trying the freeze the solution, the average kinetic energy (aka temperature) has to be lower in order for the solution to stabilize into a solid state...the formula for finding the freezing point depression and boiling point elevation are respectively as follows(replacing words in parenthesis with appropriate symbols):

(delta)T(subscript f) = (italics i)K(subscript f) x molality

(delta)T(subscript b) = (italics i)K(subscript b) x molality

where the (italics i) is the van't Hoff factor, K(subscript f) is the Molal Freezing-Point Depression Constant and K(subscript b) is the Molal Boiling-Point Elevation Constant.

too much information, anyone?
May 01, 2006

This was fun and easy until I read mabelrxu's answer.It was still but I had to get rid of the easy because of my favorite question,WHY.
May 07, 2006

Thanks to mabelrxu for answering the question "how is this possible?"

Shame the teaser answer gave us what not why...
May 12, 2006

wrong above post

any polar substance
non polar and it wont mix
May 26, 2006

Hello Kitty, if you added ice at an extremely low temperature, all you would do is freeze the water, making it all ice. The idea was for it to still be liquid.
Anything soluble is good, and the more ions produced is better. CaCl2 is better than NaCl, for instance.
Jun 17, 2006

liberalgeek. Let's be exact if we are going to bring into question somone else's post. There is not just polar and non-polar. With the exception of diatomics like nitrogen gas, everything is polar to some degree. Water is very polar, but I can still get some less polar solvents to dissolve in it. Ethanol is miscible in water but less polar. The real question is about solubility, anything that dissovles, even a little, in water will lower it's freezing point, and elevate its boiling point.

Jul 13, 2006

holy moley, much more than i wanted to know
Aug 18, 2006

Ethelyne glycol is much more effective.

(It's antifreeze!)
Oct 17, 2006

Hey! I saw that on Mythbusters.
Dec 27, 2006

this is why seawater can be so cold and not freeze .....although it does freeze eventually.... whatever ... i should've remembered the exact chemistry from last year, but sadly i didn't. I like chemistry!!!!!!
Jan 20, 2007

alcohol does the same trick. Many people keep their vodka in the freezer.
Mar 05, 2007

i wanna try thta!
Apr 15, 2007

Covering this in chemistry now. Curse you colligative properties!
Oct 10, 2014

Too much info, too much info. Now my head hurts. But I knew salt had something to do with it.

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