Sciencemadness Discussion Board

12.5% NAOCl from Grocery Store!

hodges - 26-6-2004 at 14:10

Local grocery store also sells pool chemicals in the summer. I found "Liquid Chlorinator - for chlorination of swimming pools. Active ingredient: Sodium Hypochlorite 12.5%. Store and transport upright - vented cap". Cost was $4 for 1 gallon.

swimming pools are good!

Magpie - 26-6-2004 at 18:00

I also found NaBr, Na2CO3, & Ca(OCl)2 all at 100% at pool supply stores.

The_Davster - 26-6-2004 at 18:27

The maximum concentration of NaOCl I have found is 10.8% as liquid shock treatment. 5$ for 5L

Mendeleev - 26-6-2004 at 19:47

100% Ca(ClO)2? Could you give me the name of this pool store and the name of the brand?

I am a fish - 27-6-2004 at 01:37

Quote:
Originally posted by Magpie
I also found ... Ca(OCl)2 ... at 100% at pool supply stores.


That seems unlikely. It's far more likely to be the mixture of Ca(OCl)2, CaCl2 and CaOCl2, that results from passing chlorine gas over calcium hydroxide. This mixture (known as "bleaching powder", "chloride of lime" or "calcium oxychloride";) is also sold by laboratory suppliers. For most practical purposes, it is just as good as pure hypochlorite, as chloride ions are relatively inert.

calcium hypochlorite

Magpie - 27-6-2004 at 16:17

For one year, about 10 or 15 years ago, I was maintenance manager of a neighborhood communal swimming pool. The chlorinating agent we used was calcium hypochlorite, at least that is what I remember everyone calling it and what the 40 lb drum was labeled. A year or 2 later the pool switched to the tablets which have chlorine bound in an organic compound, and I think this is probably what's used almost exclusively today for small pools.

I will be gone for a few days but when I return I'll check with the local pool chemicals suppliers to see what they have.

My trip is for fishing/relaxing in the mountains. I will be passing through a gold mining area and will stop to pick up a small iron mortar & pestle for the pulverizing of my gold ore.:D

chemoleo - 27-6-2004 at 16:24

By the way, 100% Ca(OCl)2 is a solid, so no point dealing with percentages! It is stable in isolation, unlike NaOCl. I know this because I have 500 g of this lying about :P

Organikum - 28-6-2004 at 07:28

If it says something like 60%+ available chlorine its almost pure calcium hypochlorite. If it says 30%+ its bleaching powder and if its around 90% its probably TCCA or related.

as a rule of thumb.

The_Davster - 28-6-2004 at 10:36

I have a bag of calcium hypochlorite.
It is listed as "65% Ca(OCl)2" and "65% available chlorine" So how pure is this?, the 65% Ca(OCl)2 conflicts with Organikum's statement that 65% available chlorine is almost pure hypochlorite.

pool chemical Ca(OCl)2

Magpie - 1-7-2004 at 15:39

I checked out 2 pool chemical suppliers today. They have or can get Ca(OCl)2 and say it is 65% "available chlorine." I'm thinking that this is jargon for 65% OCl as this would be the sanitizing/oxidizing part of this compound. The wt% OCl is = 102.9/142.9 = 0.72, or 72% for pure Ca(OCl)2. This seems more than a coincidence.

Also Guardex, a common US manufacturer lists its "Guardex Breakpoint Shock" as 100% Ca(OCl)2 on its MSDS at http://www.goldenc.com/acrobat/coshhsheets/Guardex/Breakpoin...

Another good site for pool chemical information is: http://www.poolandspa.com/page35.htm

[Edited on 1-7-2004 by Magpie]

hodges - 2-7-2004 at 16:25

I found calcium hypochlorite (solid) at the same grocery store. Cost just under $3 for 1 pound, comes in a white plastic bag. On the label:
Quote:

Domestic Pool Shock
For Super Chlorination
Active Ingredient: Calcium Hypochlorite 65%
Inert Ingredient: 35%
Aqua-Tek
Made in Canada

Calcium Hypochlorite

MadHatter - 11-7-2004 at 21:59

Pure calcium hypochlorite is 49.59% chlorine. The last pool shock I bought
was 93% Ca(OCl)2.

HTH swimming pool Ca(OCl)2

Magpie - 25-8-2004 at 08:49

I just bought some "HTH Super Sock It" shock treatment for swimming pools ($3 for 1 lb). On the package it says 78% calcium hypochlorite and 22% "other ingredients." Needing to know what the other ingredients were I called and obtained an MSDS (it is noteworthy that said MSDS is not available on their website). The MSDS says:

calcium hypochorite......65-90%
sodium chloride..............0-3%
calcium chlorate..............0-5%
calcium chloride..............0-5%
calcium hydroxide...........0-5%
calcium carbonate...........0-4%
water..............................8-16%

As a historical note I found that my freshman chemistry text (40+ yrs old) refers to H.T.H (high test hypochlorite) as a product that yields "almost twice as great a proportion of hypochlorite" as regular "bleaching powder."

Regular bleaching powder is made by passing chlorine over dry slaked lime:

Ca(OH)2 + Cl2 = H2O + CaCl(OCl)

This reaction is heterogeneous and does not go to completion.

JohnWW - 25-8-2004 at 13:03

"Chloride of lime" (mostly calcium hypochlorite) is very corrosive to metal containers, undergoing slow decomposition (and hydrolysis if water vapor is present) in storage. I once bought some of it in a tinned steel container in the 1960s, and after a year or so it had eaten through it.

BTW THe strongest NaOCl solution that can be bought in a supermarket as household bleach, at least in my area, seems to be 3.67 gm/liter, or 0.367 parts/100 parts water. If 12% appears to be obtainable, I would say that supermarket consumers are being ripped off, because of the extra costs of larger containers, and of carting and storing a lot more water. Its solubility ranges from 26 parts/100 parts at 0ºC to 158 parts/100 parts at 56ºC, much higher than the above concentrations. (At higher temperatures it probably decomposes).

John W.

vulture - 25-8-2004 at 13:16

Endconsumers are always being ripped off when it comes to chemicals. Ethanol, methanol, acetic acid,...etc.

The price usually is atleast 400% of what it's worth.

Polverone - 25-8-2004 at 14:04

"What it's worth" is of course "whatever people are willing to pay for it." I do agree that consumer chemical products are far more expensive, per quantity, than the industrial equivalent purchased in 55 gallon drums or even larger units. What do you expect when sodium hypochlorite solution is advertised on TV and people actually have brand loyalty to different sodium bicarbonate distributors? I can barely bring myself to care about this since lab chemicals are overpriced by another order of magnitude and hence form the "price bottleneck" that limits what I buy.

Mumbles - 28-8-2004 at 20:42

Quote:
Originally posted by JohnWW

BTW THe strongest NaOCl solution that can be bought in a supermarket as household bleach, at least in my area, seems to be 3.67 gm/liter, or 0.367 parts/100 parts water. If 12% appears to be obtainable, I would say that supermarket consumers are being ripped off, because of the extra costs of larger containers, and of carting and storing a lot more water.


There is a difference in pool bleach and washing bleach though. I'd imagine using 12% bleach on clothing may be enough to damage them. I've had 6% make a whole in my shirt before. I suppose it wouldn't be bad if all you did is add it to the wash, but if you even remove stains with it by adding directly to the article of clothing itself it may present some damage risk.

It would make sense to me to just use 12%, but half as much as 6%(the common one around here). Can't get the liquid pool chlorinator though. Also going by the prices in here 6% is still cheaper. it is $1.39 a gallon as of last week. This is still over a dollar cheaper than any of the prices mentioned so far.

I can't even get the liquid pool chlorinator. I have looked high and low in 3 different major cities not to mention countless different small community hardware stores and grocery stores. They only carry solid chlorinating granules and the HTH shock of course.

[Edited on 8-29-2004 by Mumbles]

calcium chlorate

battar30 - 30-1-2005 at 16:39

Quote:
Originally posted by Magpie
I just bought some "HTH Super Sock It" shock treatment for swimming pools ($3 for 1 lb). On the package it says 78% calcium hypochlorite and 22% "other ingredients." Needing to know what the other ingredients were I called and obtained an MSDS (it is noteworthy that said MSDS is not available on their website). The MSDS says:

calcium hypochorite......65-90%
sodium chloride..............0-3%
calcium chlorate..............0-5%
calcium chloride..............0-5%
calcium hydroxide...........0-5%
calcium carbonate...........0-4%
water..............................8-16%

As a historical note I found that my freshman chemistry text (40+ yrs old) refers to H.T.H (high test hypochlorite) as a product that yields "almost twice as great a proportion of hypochlorite" as regular "bleaching powder."

Regular bleaching powder is made by passing chlorine over dry slaked lime:

Ca(OH)2 + Cl2 = H2O + CaCl(OCl)

This reaction is heterogeneous and does not go to completion.
battar

frogfot - 5-2-2005 at 07:30

When thermally decomposing calcium hypochlorite in water it seems to evolve alot of gases (relatively nonsmelly). Anyone has a good explanation on what this may be?

I know that in presence of some catalysts as cobalt salts, on heating in water, hypochlorite will decomp to oxygene. Or maby even simpler, since product may have a carbonate (from Magpies MSDS), maby it disproportionates to CO2 (although soln is quite basic).

First explanation sounds better... if it's right, how could one "kill" all present catalysts??

Btw, my pool chock chlorine says to contain 100% calcium hypochlorite :o

neutrino - 5-2-2005 at 08:58

Try a chelating agent for the heavy metal ions. I’m not sure where you could buy EDTA, but others should work. In Mega’s hydrazine synth, for example, gelatin is used.

frogfot - 5-2-2005 at 09:45

Wouldn't formed complex dissociate at elevated temps.. I have also a feeling that theese agents will get oxidised pretty fast..

[Edited on 5-2-2005 by frogfot]

hodges - 19-12-2005 at 19:29

Quote:
Originally posted by hodges
I found calcium hypochlorite (solid) at the same grocery store. Cost just under $3 for 1 pound, comes in a white plastic bag.


Interesting followup to this. Since the chemical was packaged in a plastic bag (designed for use all at once), I needed to store this in a container. I used a 1-liter plastic bottle that used to hold a carbonated drink. I have not used this particular chemical in over a year, so most of it is still in the bottle. Recently I noticed when I grabbed this bottle that it appeared to be under pressure. I opened the top slightly and a lot of pressure was released - about like when opening a drink that has been shaken. The gas was not chlorine because it was colorless in the bottle. It did have a slight pool odor but nothing like would have been the case had it been all chlorine. I'm guessing the gas was oxygen, since hypochlorites can produce oxygen from water (usually in sunlight though). Anyway, this is something to keep in mind if storing calcium hypochlorite - open the bottle once in a while to relieve any pressure that has built up.

BromicAcid - 19-12-2005 at 21:42

Hodges, I noticed the same thing, I have a large amber jar with about 4 kg of Ca(OCl)<sub>2</sub> and it built up somewhat considerable pressure when I opened it last, like you said, it didn't seem like it was all chlorine or anything though I wouldn't doubt some being in there. My lithium hypochlorite does it to an even greater extent. Which begs the question, why are'nt the little plastic bags you buy of it from the hardward store bulging from decomosition gasses? Either 1) The plastics are permeable to the gas; 2) Something in the air is catalyzing the decomosition (doubtful); or 3) Light is causing the decomosition. As for the light I don't think that is a major factor, like I said, I have mine in an amber bottle in a dark shed and it still decomposes, so really that leaves me with the first opinion. I have to wonder how much it has decomposed in the last few years though.

woelen - 20-12-2005 at 10:47

I also noticed this, but there is quite a difference between batches. I have calcium hypochlorite 65% active chlorine from HTH, and this has a VERY strong smell of chlorine and it produces pressure. I also have 70% active chlorine stuff, which is odorless and does not result in pressure buildup.

I store the material in a thick glass bottle with a chlorine resistant cap, in which I drilled a very small hole. Over the hole I put some adhesive tape. When the bottles cools down, causing underpressure, then the air-inlet is blocked, due to the tape. Just in case the pressure would become too high, the tape will be pressed away from the hole and the gas can be released. This storage is a good compromise between safety on long-term storage and on the other hand not to have free flow of air, going in and out of the container at each thermal cycle.

The_Davster - 20-12-2005 at 15:26

I have had the same thing happen, it gave me quite the fright when I opened the mason jar of pool chlorinator after several months. Rather loud POP when I opened it. Over the last year or so I open it every month or so, it seems that the gas evolution decreases with time.

Pommie - 20-12-2005 at 20:04

Does anyone know how "available chlorine" is measured?

I can get pool chlorine that has 100g/L available chlorine for about US0.40c/L. It has a density of approx 1.2

If it only contains NaOCl then I guess it would have about 200g of NaOCl to get the density. This equates to about 95g chlorine.

So, can I assume that 1L contains 74/35*100 = 210g of NaOCl. (or the equivalent in NaCl and NaClO3)

Maybe I should just boil some down and see.

Mike.

woelen - 21-12-2005 at 10:54

It is easiest to think of it as follows:

Add an excess amount of dilute HCl to the compound you have. This produces Cl2, according to the reaction ClO(-) + 2H(+) + Cl(-) --> Cl2 + H2O.

For each gram of compound you get a certain amount of chlorine gas. Available chlorine is defined as

(weight of chlorine / weight of compound) * 100%

So, with your pool chlorine, which has 100 g/L of available chlorine, you can expect 100 grams of Cl2 gas for each liter of this product, when that is added to excess HCl.

This definition even allows for more than 100% available chlorine content. An example is the compound LiClO. From each gram of LiClO you can get 1.23 grams of Cl2, so this has 123% available chlorine.

garage chemist - 21-12-2005 at 11:09

All NaClO solutions (pool chlorine and bleach) contain NaClO and NaCl in equimolar amounts.
This results from the production by leading chlorine into NaOH solution:

2 NaOH + Cl2 ---> NaCl + NaClO + H2O

The NaCl cannot be separated from the mix, so it is just sold with the NaCl in solution too.

hodges - 25-12-2005 at 16:19

I checked again recently and there was a very slight pressure buildup of pressure in the bottle. I tried squeezing the bottle gently with a lighter held nearby, and the gas does appear to be at least partly oxygen. The flame got brighter and smaller.

Zinc - 29-6-2006 at 13:24

I can from a supermarket buy quite concentrated sodium hypochlorite solution.
On the bottle it says: sodium hypochlorite 15%-30%

Rona in Montreal...

Chemist514 - 30-6-2006 at 11:27

Supreme Shock Treatment
Extra Fine Granulation
500 grams (Wow... meets my standard supply ammount.. how nice)
Guarantee : Sodium Hypochlorite 65%
Available Chlorine Content 65%

This have any actual General Chemistry uses? I bought one anyways cause you people talked about it so much and it was like 4$. All the best peeps.

neutrino - 30-6-2006 at 14:09

Hypochlorites have many uses. There's the haloform reaction, thermal decomposition into chlorates, etc, etc.

hodges - 30-6-2006 at 17:32

Quote:
Originally posted by Chemist514
Guarantee : Sodium Hypochlorite 65%
Available Chlorine Content 65%


I think something is not right about those percentages. Is this a solution? I doubt it could be 65% by weight. But it must be a solution because NaOCl is not stable except in solution. Are you sure it wasn't <i>calcium</i> hypochlorite? 65% is a pretty standard content for this in solid form.

Another thing, if it really was 65% sodium hypochlorite wouldn't the chlorine content be 65% * 35 / (23 + 16 + 35) = 31%?

Hodges

Chemist514 - 30-6-2006 at 23:01

Ack! my bad, you are indeed correct sir... Calcium Hypochlorate . I had been trying to find another product all day long that came close to 4% sodium hydroxide and so made the typo. .

hodges - 1-7-2006 at 07:09

I just did a test on my product, which I purchased 2 years ago now. I diluted exactly 1ml of the solution with a liter of water, then tested it with pool test strips that test for "free chlorine". The results were off the scale. I dumped out half the solution and added water to make a liter again. This time, the results appeared to show 6 parts per million. I then repeated the dilution again and I got 3 parts per million, confirming the previous test.

Based on the dilution, the original solution has 4000 * 3 parts per million = 12 parts per thousand = 1.2 parts available chlorine per hundred. So therefore the NaOCl concentration would be (23 + 16 + 35) / 35 * 1.2% = 2.5%.

Orignially it had (according to the label, I never measured it) 12.5% NaOCl. So that would mean that in 2 years, 80% of the NaOCl was lost. Is this a reasonable average rate for decomposition of NaOCl solution? The bottle was kept in the dark and the temperature was always between 70 and 80F.

It appears the grocery store no longer sells this. I'll have to try getting some regular bleach and seeing what percentages I get.

Hodges

hodges - 4-7-2006 at 14:50

I did a titration using Na2S2O3 and KI. First I made a 0.02M solution of Na2S2O3 using 3.3g in 1 liter of water (I used slightly more than calculations in case any moisture was present in the Na2S2O3 (which was supposed to be anhydrous). To test the old swimming pool chlorinator, I diluted it 99:1 with water. I then added some 3M H2SO4 and excess KI. The result was a solution containing iodine. I titrated this against the Na2S2O3 solution.

The reaction are (taken from http://web.lemoyne.edu/~giunta/chm151L/bleach.html):
OCl- + 2 I- + 2 H3O+ --> I2 + Cl- + 3 H2O
I2 + 2 S2O32- --> 2 I- + S4O62-
Therefore, my 0.02M Na2S2O3 solution would titrate 1:1 with bleach that was 0.01 molar (which would be 1 molar originally, since I diluted it 99:1).

I titrated by adding Na2S2O3 carefully until all iodine color disapeared. I found that for 100 drops of the bleach solution, I only needed 13 drops of the Na2S2O3 solution. Therefore, my old swimming pool chlorinator is only 0.13M. The calculated concentration of NaOCl is then 0.13 * (23 + 16 + 35) / 1000 = 9.6g per liter = 0.96%.

This did not seem right. So I titrated some new bleach which was supposed to be 6% NaOCl. My titration showed it as 5.5% NaOCl. Probably close enough since the 6% it left the factory with would be a maximum.

So then, how could I have gotten 2.5% by testing the swimming pool chlorinator solution with the pool test for free chlorine? Apparently, "free chlorine", when testing swimming pools, means something a bit different than the chemistry definition. Apparently it really means "free sodium hypochlorite". When I calculated 12 parts per thousand using the test strips, this was not the amount of chlorine but the amount of sodium hypochlorite. That agrees pretty closely with the 0.96% I got by titration, given the difficulty in reading the exact value based on color.

Its really strange that "available chlorine" would really mean "total sodium hypochlorite". However, I see another item of evidence for this. To test for available bromine instead of available chlorine you are supposed to multiply the values by 2. If it was only testing the amount of OCl-, or OBr-, this would not be necessary.

Hodges