Friday is here, and the 'A Taste of Science for the Weekend' corner is back — number 71.
This time: how salt dehydrates and destroys living cells through… statistics!
-
When an acid and a base neutralize each other, the product of their reaction is a salt.
Salt is an ordered lattice (crystal) of positively charged ions (cations) and negatively charged ions (anions). The ions are bound tightly to one another, like tiny magnets.
-
Osmosis is a process in which a solvent — water, for example — is drawn through a thin filter (membrane) from the side where solute concentration is low toward the side where solute concentration is high.
For instance: if you divide a water-filled container with a thin membrane and dissolve a large amount of salt on one side, the water on the other side will tend to migrate toward the side with the high salt concentration.
The reason for this is fascinating, and it has everything to do with statistics.
-
The reason salt dissolves in water is that water molecules have a positive pole and a negative pole, much like batteries.
The poles of the water molecules are attracted to the positive and negative ions of the salt, effectively pulling it apart.
Each dissociated salt ion becomes surrounded by water molecules bound to it, which significantly reduces the number of free water molecules.
On the other side — where no salt is dissolved — all the water molecules are free and move about unhindered, which statistically increases the likelihood that they will strike the membrane and pass through it to the salt side.
On the salt side, only a small number of molecules are not bound to ions, so statistically fewer of them will cross back through the membrane to the other side.
-
A concentration of salt outside a living cell can kill it.
The water inside the cell passes outward through the cell membrane, which acts as a semi-permeable membrane. The proteins left behind without water break down and denature in an uncontrolled manner, and the cell dies within a short time.
-
Certain animals and plants have developed resistance to saline environments through one of two strategies.
The first is maintaining a high internal salt concentration that balances the salt outside the cell.
Certain bacteria live this way (halophiles), and it is a remarkable adaptation, since the entire architecture of the cell must be tuned to function in a salty environment.
The second strategy is raising the concentration of solutes inside the cell, but using sugar-based compounds and organic molecules that do not interfere with the cell's normal functioning.
-
The breathtaking location in the video is entirely real.
It is the world's largest salt flat — the Salar de Uyuni — located in southwestern Bolivia.
During the rainy season, a thin layer of water transforms the salt flat into a mirror that reflects the sky; when the rain stops, the salt dries out and gives it the appearance of a lunar landscape.
It is an important resource for the regional salt industry, and a tourist attraction that draws visitors from around the world.
Shabbat Shalom 😊
--
If you enjoy this corner, you're welcome to follow along and catch it again next week.
Video credit: Adrien Raza on YouTube
#taste_of_science_for_the_weekend