FRIHOST FORUMS SEARCH FAQ TOS BLOGS COMPETITIONS
You are invited to Log in or Register a free Frihost Account!


Strange Salt Phenomenon





Soltair
This year in our chemistry class we had to do a simple lab that consisted of measuring the impact of salt addition over the boiling point of water. However, it turned out that this simple-looking lab was somehow the most dangerous of the year! When water boils, if you add salt, it vaporizes all at the same time. I have not witnessed this phenomenon myself, but people got hurt (mostly burned by the "exploding" solution) and our class had to boil separate samples of water instead of continuously increasing the concentrations of salt.

Knowing that more salt in the water usually raises the boiling point, what scientific explanation could actually justify this reaction? Is it because the energy freed by the new physical links between molecules and atoms is released before the true boiling point shift happens?
qsmith
From what I remember of reading somewhere....

What boiling is, is when the kinetic energy in some of the water molecules of the water is sufficient to create gas pockets in the liquid where the pressure of the gas is more than the pressure in the water. Close to the surface of the water this is close to the air pressure. What prevents all the water to boil at once is the co-hesive links between the water molecules. this in turn causes the initial gas bubbles to form around microsocpic impurities in the liquid as well as uneven surfaces in the container.

Now when at this point you add a large quantity of any impurity in solid form (fine crystals or sand) you suddenly provide many surfaces and angles that allow millions of bubbles to form at the same time instead of a few hundred at a time - This will then cause the rapid conversion of the liquid to gas and in "ideal" circumstances, an explosion.

Shocked
Gagnar The Unruly
Which is why pots always boil from the bottom and sides, and not in the middle, and why air bubbles get bigger as they get to the top of the water. The water in the middle superheats and can't boil until it get's disturbed. My guess is that the 'explosion' would only be violent if the water was just starting to simmer and was superheating but not in full boil, and I wonder if it would be more likely to happen if the lab was using high-purity distilled water!
qsmith
Yes - never tried this but NEVER boil distilled water in a micowave oven....
Gagnar The Unruly
Not sure it ever would've occurred to me, but duly noted nonetheless!
Soltair
That makes sense, and we did use distillated water I think. It may explain this "excessive" reaction. Poor guys around got burned on the arms and even lost a bit of skin... Not that fun at all. Confused

Anyways, I hope I didn't give away a cheap way to do bombs for wannabe bank thieves... Wink
squirrelmaster
Soltair wrote:
That makes sense, and we did use distillated water I think. It may explain this "excessive" reaction. Poor guys around got burned on the arms and even lost a bit of skin... Not that fun at all. Confused

Anyways, I hope I didn't give away a cheap way to do bombs for wannabe bank thieves... Wink

riiight, i can't see how a small explosion like that would ever actually destroy something like dynamite would in a bank robbery Laughing

Have you ever microwaved a compact disk shiny side up, its real cool, but it will break your microwave and present fire hazards
(just look here, do not try unless you just hate your microwave and CD)
Related topics
Help Me Out With A Strange Page Phenomenon!
Musings on agnosticism
Conservative Christian Dictionary.
What's great about your country?
Strange sky sounds around the world
[php scripts ] phpweather&email
Strange Fire fox problem
Strange Mysql-database
My list of musics
Strange "mysql_num_rows()" error (Solved)
Seriously strange Phpbb forum problem
Hollaback Girl
Strange cracking sound in converted mp3
Fashionable Nonsense by Alan Sokal and Jean Bricmont
Reply to topic    Frihost Forum Index -> Science -> General Science

FRIHOST HOME | FAQ | TOS | ABOUT US | CONTACT US | SITE MAP
© 2005-2011 Frihost, forums powered by phpBB.