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Re: salt water caps and chem.



Tesla List wrote:
> 
> Original Poster: "chris morgan" <crmorgan-at-hotmail-dot-com>
> 
> alright, when ya make a salt water caps ya dissolve NaCl in water and
> dissisociates into Na+ and Cl-(or is it the other way
> around...)anyway,you then procede to pump electrons in or out. 

Yep. 

> Wouldn't the Na trap them in it's electron orbits.  Some one on this list
hast to > know more about chemistry than me.  

Nope. When NaCl dissolves, it creates an ionic solution, and in the
process the sodium and chloride ions undergo "solvation", combining with
the water to become hydrated. Negatively charged areas of nearby polar
water molecules become electrically attracted to, and associated with,
the positively charged sodium ions (cations). A similar thing happens
with the chloride ions (anions). In a sodium chloride solution, each
sodium ion "carries" with it about 7.4 water molecules. 

The presence of the surrounding water molecules has the impact of
reducing the "attractiveness" of a sodium ion to free electrons, as well
as to nearby chloride ions - once dissolved, the ions tend to stay in
solution. Sodium ions DO combine with free electrons at the cathode,
dehydrating in the process. However any neutral sodium atoms that might
be formed immediately combine with the surrounding water to liberate
hydrogen gas and re-form sodium ions.  

> Would this effect capacitance at all?

Nope, since the capacitance is governed by the area of the conductive
plates (water in this case), the glass dielectric's wall thickness, and
the glass's dielectric constant. Any "resistance" added by the saltwater
solution simply acts similar to a resistor connected in series with the
slatwater cap, but does not alter its capacitance value. This additional
resistance DOES tend to make the capacitor more lossy than if you used
metal plates, since there's now relatively larger ohmic (I^2R)losses
involved.
> 
> Chris, via the inter-thingy
> 
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Hope this helps!

-- Bert --