SWG What happens to the sodium? question for the chem folks

[diniba69]

I remember when I was a kid in HS and my teacher dropped a "pill" of sodium into a glass of water and showed us how it violently skipped across the surface. It seemed like it would not mix with water. My questions are :
1. So after a SWG produces the CL..what happens to the NA?
and
2. I read somewhere that after the CL is used...it turns back into salt ...is this true ? If so how?

I havn't taken a chem class since early college.1990s...so dumb down the answer for me if you can.

thanks

Brian

 

[mas985]

Chemgeek has a good explaination in this post.

[Edit] Just read the post again and he doesn't really say much about sodium but I think it stays as a sodium ion in solution or NaOH (sodium hydroxide) until it recombines with the chlorine.

Here is a better explaination.

 

[chem geek]

The sodium in the solid "pill" of sodium experiment is atomic sodium which violently reacts with water. That is totally different (in a different oxidation state) than the sodium more commonly found in a variety of chemicals including that in bleach, chlorinating liquid, lye, etc. The sodium in most chemicals is such that the chemical dissolves in water resulting in the sodium simply being a charged sodium ion in the water. It doesn't react with anything and has nothing to do with the saltwater chlorine generator (SWG) except that it provides for greater electrical conductivity which is needed for the reactions in the SWG. It does not, however, directly participate in those reactions.

In an SWG it is the chloride ion that participates in the reaction in which it becomes chlorine gas and then hypochlorous acid. At the other plate, hydrogen ions in the water become hydrogen gas. As you can see, sodium wasn't mentioned and did not directly participate chemically in the SWG.

Richard

 

[diniba69]

In an SWG it is the chloride ion that participates in the reaction in which it becomes chlorine gas and then hypochlorous acid. At the other plate, hydrogen ions in the water become hydrogen gas. As you can see, sodium wasn't mentioned and did not directly participate chemically in the SWG.

Richard

thanks...question answered ...but does the used hypochlorous acid then turn back to NACL? I think I heard that somewhere... unless I am hallucinating from all the shock I used the last few days!!!

 

[JasonLion]

Remember that sodium and chloride are disassociated in the water. When you speak of salt, you really mean a sodium and a chloride. The sodium just sits there and does nothing. The chloride is transformed into hypochlorous acid by the SWG, and then turns back into chloride when the chlorine gets used up. There may be several chemicals steps before it gets all the way back to chloride, but it generally will get back to chloride eventually.

In the end you have a sodium and a chloride, which is what you started with. If you let the water evaporate, you would be left with salt, just as you had in the beginning.

 

[diniba69]

Thanks Jason, Richard, and Mas

I forgot about the whole Ion in a solution thing. Makes sense to me now. You guys saved me a trip down to the science department of the school I work for!...I promise I won't start bugging you about atomic numbers, nuetrons, protons and the such