What effect does sodium have

[Mac Roe]

Hi Chem Geek or anybody who would like to respond - Tuesday, 2012 March 06 - 00:05:22 (day#066)

* Thank you for your extensive analysis of chlorinated pool chemicals * I have one question that has always disturbed me > What effect does sodium have on all parts of a pool system? * Not being a chemist , merely a lowly physicist , I understand Na to be a very reactive metal * It seems that this would be quite harmful to a pool system > pumps , pipes , lining * What do you have to say about this ?* Does the Na build-up in the pool or does it disappear somehow ?*

* BTW , I lived in Novato for 2.5 years back when horses (with riders) would march down the street * Ah , yes , the memories when a friend worked in the 101 Cafe and Novato was a notorious traffic bottleneck *

Mac

 

[JasonLion]

Sodium ions have no significant effect at the levels they are likely to occur at. If the level were to get too high, there could well be corrosion problems, but that is fairly unlikely.

Quite a few common pool chemicals add Na to the water, including all forms of chlorine. These constant additions are balanced out by long term water replacement, especially in outdoor pools. The amounts of Na added are fairly low and the acceptable levels are quite large relative to the amount added, so it really doesn't take all that much water replacement to keep the levels under control. If you lower the water level in the winter for winterizing you are certainly fine. Splash out from kids swimming is also generally sufficient on it's own. There can be rare cases where water replacement is especially slow (no backwashing, no winterizing, little swimming, lots of chlorine use) where it can become an issue, but that is really quite unusual.

 

[JamesW]

I understand Na to be a very reactive metal

Just to be clear, sodium, the metal, is reactive, but sodium, the ion, is not. Alkali metals have a lone electron in their outermost valence shell. This lone electron is readily lost, which is what make the metal so reactive. For example, the reaction with water is as follows:

2Na_(s) + 2H₂O --> 2Na⁺ + 2OH^- + H_2(g)

Sodium metal + water --> 2 sodium ions + 2 hydroxide ions + hydrogen gas.

The reaction happens very quickly, and is highly exothermic (gives off heat). Once the sodium loses its lone valence electron, it becomes a very stable ion and unreactive because it has a full valence shell of eight as shown in the image below.

Note: The image shows the sodium atom as the metal with the outer single electron. Once the outer electron is lost, the outer electron shell is the second shell with eight electrons.

 

[Mac Roe]

Thank you Jason & James - Tuesday, 2012 March 06 - 20:25:27 (day#066)

* Thanks for your immediate and detailed explanation for what happens to sodium when introduced into a pool * It puts my concerns to rest as it has always bothered me *

* Do you or anybody have an opinion about Hypochlorous Acid ?* It doesn't seem to be available and sales people continue to get it confused with Hydrochloric Acid *

Thanks from Australia
Mac

 

[Bama Rambler]

You can't buy Hypochlorous acid directly. You buy hypochlorite (sodium or calcium most commonly) and it turns into hypochlorous acid as it dissolves in the pool water.

 

[JamesW]

Thanks for your immediate and detailed explanation for what happens to sodium when introduced into a pool * It puts my concerns to rest as it has always bothered me *

Just to be sure that there is no confusion. Sodium, as a metal, is not used in any pool products. Any sodium is added in the form of an ion. For example, sodium chloride dissociates into sodium ions and chloride ions.

 

[Lershac]

Sodium in pure form is not used in pool maintenance.

This is what pure sodium does in water::



[youtube:tpihxy81]RAFcZo8dTcU[/youtube:tpihxy81]

 

[teapot]

Oh yes you can just make out the outer valence electron breaking free producing the exothermic reaction :lol: