Reef Chemistry Question of the Day #258 Balling Sodium Chloride-Free Salt

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #258

The Balling method uses calcium chloride as a calcium supplement and sodium bicarbonate/carbonate for alkalinity.

After calcium carbonate is deposited through calcification by corals and other creatures, and by abiotic precipitation, sodium and chloride remain.

In order to prevent the water from becoming too strongly dominated by the accumulating sodium and chloride, the Balling method adds a sodium chloride-free salt mix, that essentially adds all of the other components in a salt mix, minus sodium chloride. That addition keeps the ions at natural ratios.

Which chemical listed below must be present in this sodium chloride-free salt mix at the highest weight based concentration?

A. Potassium
B. Calcium
C. Magnesium
D. Sulfate
E. Carbonate

Good luck!

























.

 

[Crabs McJones]

Going with C. Magnesium

 

[Greenstreet.1]

I say magnesium also

C.

 

[beaslbob]

c magnesium

 

[JimWelsh]

While I know what answer @Randy Holmes-Farley is going after here (and it's NOT "C. Magnesium"), I'm going to respond with "None of the above." The answer is really "F. Chloride".

"But, wait!" you might ask, "How can sodium chloride free salt possibly have chloride as its largest component by weight? That makes no sense at all!"

First, I must ask how the "sodium chloride free salt" is formulated in the first place. Salt mixes are mixtures of different salts (duh) such as, for instance, sodium chloride, sodium sulfate, magnesium chloride, and/or magnesium sulfate (among others). Just looking at these four salts, it is possible to provide the necessary amount of sodium using just sodium chloride alone, or perhaps instead, using a mixture of sodium chloride and sodium sulfate. Similarly, it is also possible to provide the necessary amount of magnesium using just magnesium chloride, or you could perhaps use a mixture of magnesium chloride and magnesium sulfate. As you can see from these two examples, it is possible to source the necessary sulfate from either sodium sulfate or magnesium sulfate, or perhaps a mixture of the two.

For example, there is the oft-cited Millero recipe for an ASW mix that matches NSW levels for all the major ions:

23.98 g sodium chloride
5.029 g magnesium chloride
4.01 g sodium sulfate
1.14 g calcium chloride
0.699 g potassium chloride
0.172 g sodium bicarbonate
0.100 g potassium bromide
0.0254 g boric acid
0.0143 g strontium chloride
0.0029 g sodium fluoride
Water to 1 kg total weight.

However, this different recipe will produce the same concentrations of all the major ions as the Millero recipe. The only difference is what compounds the ions are sourced from:

27.27 g sodium chloride
3.389 g magnesium sulfate
2.33 g magnesium chloride
1.14 g calcium chloride
0.699 g potassium chloride
0.172 g sodium bicarbonate
0.100 g potassium bromide
0.0254 g boric acid
0.0143 g strontium chloride
0.0029 g sodium fluoride
Water to 1 kg total weight.

As you can see, only the first three ingredients changed; the remaining ingredients are all the same. So, my first point is that the amount of NaCl that needs to be added to "NaCl-free" salt in order to make it match NSW depends on the exact formulation of the "NaCl-free" salt. If you remove all the NaCl from Millero's recipe there is still significant Na and also Cl left in the "NaCl-free" salt mix! In fact, there is 3.29 g more NaCl left when you remove the NaCl from Millero's recipe than if you were to remove the NaCl from the second recipe!

But, let's take a look at that second recipe, which is designed to maximize the amount of NaCl used, leaving virtually no Na remaining once we remove the NaCl (except for the small amount of Na from the sodium bicarbonate and sodium fluoride). After we remove the NaCl from that recipe, there is still 2.803 g of chloride remaining from the magnesium chloride, calcium chloride, potassium chloride, and strontium chloride that the recipe calls for. And that 2.803 g of chloride is more than the next most abundant ion by weight that remains in the recipe after removing the NaCl (the one @Randy Holmes-Farley is after).

So, the answer is "F. Chloride".

 

[Crabs McJones]

While I know what answer @Randy Holmes-Farley is going after here (and it's NOT "C. Magnesium"), I'm going to respond with "None of the above." The answer is really "F. Chloride".

"But, wait!" you might ask, "How can sodium chloride free salt possibly have chloride as its largest component by weight? That makes no sense at all!"

First, I must ask how the "sodium chloride free salt" is formulated in the first place. Salt mixes are mixtures of different salts (duh) such as, for instance, sodium chloride, sodium sulfate, magnesium chloride, and/or magnesium sulfate (among others). Just looking at these four salts, it is possible to provide the necessary amount of sodium using just sodium chloride alone, or perhaps instead, using a mixture of sodium chloride and sodium sulfate. Similarly, it is also possible to provide the necessary amount of magnesium using just magnesium chloride, or you could perhaps use a mixture of magnesium chloride and magnesium sulfate. As you can see from these two examples, it is possible to source the necessary sulfate from either sodium sulfate or magnesium sulfate, or perhaps a mixture of the two.

For example, there is the oft-cited Millero recipe for an ASW mix that matches NSW levels for all the major ions:

23.98 g sodium chloride
5.029 g magnesium chloride
4.01 g sodium sulfate
1.14 g calcium chloride
0.699 g potassium chloride
0.172 g sodium bicarbonate
0.100 g potassium bromide
0.0254 g boric acid
0.0143 g strontium chloride
0.0029 g sodium fluoride
Water to 1 kg total weight.

However, this different recipe will produce the same concentrations off all the major ions as the Millero recipe. The only difference is what compounds the ions are sourced from:

27.27 g sodium chloride
3.389 g magnesium sulfate
2.33 g magnesium chloride
1.14 g calcium chloride
0.699 g potassium chloride
0.172 g sodium bicarbonate
0.100 g potassium bromide
0.0254 g boric acid
0.0143 g strontium chloride
0.0029 g sodium fluoride
Water to 1 kg total weight.

As you can see, only the first three ingredients changed; the remaining ingredients are all the same. So, my first point is that the amount of NaCl that needs to be added to "NaCl-free" salt in order to make it match NSW depends on the exact formulation of the "NaCl-free" salt. If you remove all the NaCl from Millero's recipe there is still significant Na and also Cl left in the "NaCl-free" salt mix! In fact, there is 3.29 g more NaCl left when you remove the NaCl from Millero's recipe than if you were to remove the NaCl from the second recipe!

But, let's take a look at that second recipe, which is designed to maximize the amount of NaCl used, leaving virtually no Na remaining once we remove the NaCl (except for the small amount of Na from the sodium bicarbonate and sodium fluoride). After we remove the NaCl from that recipe, there is still 2.803 g of chloride remaining from the magnesium chloride, calcium chloride, potassium chloride, and strontium chloride that the recipe calls for. And that 2.803 g of chloride is more than the next most abundant ion by weight that remains in the recipe after removing the NaCl (the one @Randy Holmes-Farley is after).

So, the answer is "F. Chloride".

;Inpain My head hurts

 

[dragon99]

D. sulfate

 

[Greenstreet.1]

;Inpain My head hurts

Your head hurts. I need a drink after that[emoji12][emoji23]

 

[Chuk]

Sulfate is the next highest component of saltwater at ~.25%

 

[Hans-Werner]

Jim is right. The answer is "F. Chloride".

 

[Christoph]

Sulfate

 

[Randy Holmes-Farley]

While I know what answer @Randy Holmes-Farley is going after here (and it's NOT "C. Magnesium"), I'm going to respond with "None of the above." The answer is really "F. Chloride".

"But, wait!" you might ask, "How can sodium chloride free salt possibly have chloride as its largest component by weight? That makes no sense at all!"

I don't disagree with the analysis, but it doesn't answer the question asked, which I was very careful to word:

"Which chemical listed below"

lol

Even then, I'm sure there is one actual answer that Hans-Werner and others have developed, but could be either of two answers, depending on what assumptions are made for the amount of magnesium that gets incorporated into the deposited calcium carbonate, and wanting to still retain a NSW ratio of ions left behind.

 

[GodfathR]

D. Sulfate

 

[dragon99]

I don't disagree with the analysis, but it doesn't answer the question asked, which I was very careful to word:

Some people don't do well on standardized testing.

 

[Hans-Werner]

Wow, he´s got the turn. The next one is sulfate, far ahead to the other ions. With chloride included it would have been a bit more difficult. SO4 ist just heavy, weight based.

 

[JimWelsh]

I don't disagree with the analysis, but it doesn't answer the question asked, which I was very careful to word:

Yes, I know, and I saw how carefully you had worded it, but I'm curious: Why did you choose to leave chloride out of the list?

 

[Randy Holmes-Farley]

Yes, I know, and I saw how carefully you had worded it, but I'm curious: Why did you choose to leave chloride out of the list?

Although not mentioned in the question, I wanted folks to think more about what was being added from a functional standpoint, not necessarily a practical one of how that is accomplished. As you noted there are many ways to make a sodium chloride free salt mix with different actual amounts of sodium and chloride. The amount of chloride can be reduced by using no sodium in the formulation, but I agree even at a minimum, it is still somewhat more than the sulfate (see assumptions below). But getting to that number and whether the chloride is above or below sulfate was beyond what I was expecting from the question. I didn't know it either until I ran it just now.

FWIW, I do not know if it does or not in commercial applications of "Balling", but I assume that sodium chloride free salt mix actually also contains little to no calcium (or maybe little to no carbonate/bicarbonate), or else that might precipitate calcium carbonate in the mix, and that reduces the added chloride quite a bit if you leave it out.

I still have to address assumptions relating to magnesium incorporation in the calcium carbonate, and how that might impact the answer, but that's for later.

 

[mcarroll]

https://www.reef2reef.com/threads/abundance-of-elements-x-periodic-table.139694/

Mg is next on the list if we're literally omitting sodium and chloride, but based on the discussion I'm not sure I understood the question – maybe that's not what we're doing.

 

[Randy Holmes-Farley]

OK, so the answer, in the absence of any allowance for incorporation of magnesium into calcium carbonate, is...

Which chemical listed below must be present in this sodium chloride-free salt mix at the highest weight based concentration?

A. Potassium
B. Calcium
C. Magnesium
D. Sulfate
E. Carbonate

Simply put, it is the highest mass component of those listed in an ordinary salt mix (it is #3 overall, after sodium and chloride), and since we are intending to maintain the ratio of them all in the tank, the ratio must be the same in the NaCl free salt mix.

In upcoming posts, I'll adjust the assumption for magnesium incorporation of magnesium into the calcium carbonate and see if it impacts the answer.

 

[Greenstreet.1]

Got it wrong but I learned something new. Thank you.