A question (salt bridge)
Martin Ystenes
>Hello,
>
>I have a question about "salt bridge".
>I recall that it is related to an interaction between two groups of
>opposite net charges. But then how does this differ from ionic bond ?
>Could anyone tell me the difference between "salt bridge" and "ionic
>bond" or recommend me any reference for this ?
>Thank you very much for your time !
I´ve got a feeling that you are mixing up something. In my vocabular
a salt bridge has nothing to do with chemical bonds. It is a U-shaped
glass tube filled with a gel with a high content of salts. This
tube is used to make a "salt bridge" between two chambers (i.e. beakers)
of a galvanic cell. Due to its salt content it conducts electricity
and one can make a closed circuit. The direct contact between the
solutins in the two beakers must be avoided as they would react with
eachother instead.
Martin Ystenes
Ted Heise
sep...@pollux.usc.edu (S. Park) writes:
>I have a question about "salt bridge".
>I recall that it is related to an interaction between two groups of
>opposite net charges. But then how does this differ from ionic bond ?
>Could anyone tell me the difference between "salt bridge" and "ionic
>bond" or recommend me any reference for this ?
A salt bridge is used in electrochemistry to complete a circuit
between two half cells. It allows a flow of current without bulk
exchange of ions. Porous membranes or gels are often used.
Check any undergraduate level instrumental analysis textbook.
Ted Heise
|-- Theodore Heise ----------------------- the...@netins.net --|
|-- Omaha, Nebraska USA --- Principles before personalities! --|
Keith Warren Rickert
>sep...@pollux.usc.edu (S. Park) wrote:
>>Hello,
>>
>>I have a question about "salt bridge".
>>I recall that it is related to an interaction between two groups of
>>opposite net charges. But then how does this differ from ionic bond ?
>>Could anyone tell me the difference between "salt bridge" and "ionic
>>bond" or recommend me any reference for this ?
>>Thank you very much for your time !
>Ive got a feeling that you are mixing up something. In my vocabular
>a salt bridge has nothing to do with chemical bonds. It is a U-shaped
>glass tube filled with a gel with a high content of salts. This
>tube is used to make a "salt bridge" between two chambers (i.e. beakers)
>of a galvanic cell. Due to its salt content it conducts electricity
>and one can make a closed circuit. The direct contact between the
>solutins in the two beakers must be avoided as they would react with
>eachother instead.
No, he's not mixing things up.
In protein structures, interactions between oppositely charged groups
are often referred to as salt bridges.
The difference between that and an ionic bond is a matter of context
and degree. The basic forces causing the interaction are the
same in both cases. Ionic bond, however, is terminology usually used
when referring to the forces holding together an ionic solid, such
as salt itself.
The salt bridge terminology is generally used in a biological macromolecule
context, and often tends to imply a) a somewhat weaker interaction than
is seen in an "ionic bond" and b) that there are multiple other
factors contributing to the structure.
As I said above, though, this is all sort of usage and context,
and as such will vary among different people.
Keith
--
Keith Rickert | "The time is now. The chains of Fenric have
ke...@imppig.caltech.edu | shattered. The gods have lost the final battle.
ric...@cco.caltech.edu | Dead men's ship has slipped its moor, and the
| great ash itself trembles to its roots."