Freezing Point
Science brain teasers require understanding of the physical or biological world and the laws that govern it.
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?
Answer
By adding salt to water, you lower the freezing point of the water. If you add enough, it is possible to get it 20 degrees below the typical freezing point.
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Comments
signmeup74   
Mar 27, 2006
| You can also raise the boiling point the same way. Good job, Swaffy!!  |
fem81uk 
Mar 27, 2006
| I've obviously learnred something at college! |
AZTTT 
Mar 27, 2006
| Hence the science behind home-made ice cream! good job. Keep em coming. |
luvmyself 
Mar 27, 2006
| you learn something new everyday =) nice one! |
hellokitty593 
Mar 30, 2006
| I thought is was ice. |
brainjuice
Apr 02, 2006
| i got it right! nice one.. |
Winner4600
Apr 06, 2006
| yay i got it right!!! |
ChrisKing
Apr 21, 2006
| You learn something new every day!!!!   |
GeniusGod
Apr 23, 2006
| It was very very very easy. |
mabelrxu
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?  |
Onslaught
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.  |
_numpty_
May 07, 2006
| Thanks to mabelrxu for answering the question "how is this possible?"
Shame the teaser answer gave us what not why... |
liberalgeek
May 12, 2006
| wrong above post
any polar substance
non polar and it wont mix |
udoboy
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. |
dantak
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.
Tschuss |
speedqueenkmw
Jul 13, 2006
| holy moley, much more than i wanted to know  |
vbguy101 
Aug 18, 2006
| Ethelyne glycol is much more effective.
(It's antifreeze!) |
ttviper
Oct 17, 2006
| Hey! I saw that on Mythbusters. |
i_luv_2_read
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!!!!!! |
vikingboy
Jan 20, 2007
| alcohol does the same trick. Many people keep their vodka in the freezer. |
MelkorDCLXVI
Mar 05, 2007
| i wanna try thta!
cool!
|
Caim
Apr 15, 2007
| Covering this in chemistry now. Curse you colligative properties! |
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