Kind of Need to Know Thread

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August 6th, 2020 at 4:01:04 AM permalink
odiousgambit
Member since: Oct 28, 2012
Threads: 154
Posts: 5052
OK, this is one you probably can skip but 'might' like to know, especially if you have hard water

For a fact I had a hell of a time finding this comment, or one similar, to explain why if you have hard water like I do, one of the best ways to handle it is to use a water softener that uses salt - NaCl that is

This classic type of water softener* works by ion exchange. But I couldn't understand why it was better to exchange two sodium ions for one calcium ion**, which is what the softener does. Sodium seems like a bad choice, it's the bad boy in so many other instances, including the effects it can have on health. Why would you want that exchange ? I pondered this for a long time and it occurred to me that the problem with hard water is more to the fact that it clogs things up over time, especially at hot water exit points or where evaporation is taking place otherwise. It also makes detergent not work as well, but it does actual damage to appliances with the former problem. So it finally hit me: sodium compounds probably just tend to readily stay in solution, while calcium compounds want to precipitate out. 

I had looked over information on water softeners and never seen this explained, not in pamphlets nor on the internet. When you search for information on softeners, the softener system companies dominate, and they oddly are reluctant to talk about this. Of course scientific facts don't help sell the systems, but you would think the information would be there if you dug for it. I at least was having trouble finding it. 

Finally though, searching for solubility, I found this. 

Quote: link
...  some [minerals] dissolve more easily than others. You could easily dissolve about 360 g of table salt in a liter of water, but the solubility of calcium carbonate is only about 0.01 grams per liter. That's partly due to the fact that the ions in sodium chloride, Na+ and Cl-, have lower charges than the ions in calcium carbonate ... The higher the charges on the ions, the stronger their electrostatic attraction for each other, and the harder it is for the water to pull them apart. It's a good thing, too; if the calcium carbonate in marble were to dissolve too easily, think of how many buildings and statues would dissolve in the rain.


https://employees.csbsju.edu/cschaller/Principles%20Chem/imf/SPsolubility.htm

* I had a salt-free system that came with the house. It was very mysterious as to how it was supposed to work, you added nothing to the system to make it work. I read up on it and it made the claim that it changed the nature of the white minerals in hard water in some way but did not remove them. So though it was nice not to have to deal with big bags of salt, it did not work all that well, we had a worsening problem with the clogging. Locally, the people who install and service softeners are hard core salt type and I gave up on trying to get the salt free system serviced. This was partly due to the unhelpful information put out by the salt-free companies about how to go about service or self-service either, and partly due to a mistrust that we would ever really be happy with it. Except for no bags of salt, that part was great!

You can visualize how 'changing the nature' of the hard water theoretically might work by noting the effect adding some white vinegar has; for example adding just a bit keeps jars from getting covered with white minerals when you can food. There are softener systems that use something similar, but the system I had did not seem to be this. 

**or magnesium, maybe others
I'm Still Standing, Yeah, Yeah, Yeah [it's an old guy chant for me]
August 6th, 2020 at 7:08:03 AM permalink
gamerfreak
Member since: Feb 19, 2018
Threads: 4
Posts: 527
Some more fun salt related facts...

It seems to be a common misconception that a saltwater pools use salt instead of chlorine to sanitize the water. However, a salt water pool is still a chlorine pool, it just produces it’s own chlorine.

Saltwater pools are equipped with a chlorine generator. It applies current through a cell of metal plates, and the chemical reaction adds an oxygen molecule to NaCl resulting in NaOCl, or Chlorine/Household Bleach.

When an organic compound is killed by the Chlorine, it turns back to salt, so the pool only requires adding more salt when it’s diluted by rainwater or refill.

September 19th, 2020 at 3:34:27 AM permalink
odiousgambit
Member since: Oct 28, 2012
Threads: 154
Posts: 5052
"10 things about the universe we may never understand"
I'm Still Standing, Yeah, Yeah, Yeah [it's an old guy chant for me]
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