Talk:Sodium bicarbonate

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The article text seems to disagree with the summary table on the decomposition temperature of this compound. Article states 60degC whilst table says 300. Can someone clear this up? Drw25 16:35, 13 Mar 2005 (UTC)

In my chemistry class we did an experiment involving this. I believe that it is 60 degrees celsius. We placed it in a beaker of hot water as part of the experiment and it melted. The water was not boiling, so it was less that 100 degrees celsius.

No no, it dissolved at much less than 100°C, but as to the decomposition...see below. --M1ss1ontomars2k4 (T | C | @) 23:58, 1 June 2006 (UTC)
Correction--it could have _melted_, but not in a water bath. --M1ss1ontomars2k4 (T | C | @) 00:00, 2 June 2006 (UTC)

Contents

[edit] Error in image

I removed the erroneous image from the table. Not only was it poorly drawn, it also showed a covalent bond between sodium and oxygen. This could mislead beginners in chemistry. Walkerma 05:10, 11 May 2005 (UTC)

[edit] Confusing wording

What does "to help water down taste" mean?

When you down it. It helps the water taste like water.

Edit: No it helps "water" down the taste. Water in this instance means to make the substance less flavorful, ie tasting like water...

It's a compound verb: "to water down." It should mean, "to dilute." In other words, you add water to something to dilute it.

Things besides water may be added to dilute solutions (saline solutions etc.). Dilution is not so much "to add water to" as it is "to decrease the concentration of" Jvbishop 13:05, 30 March 2007 (UTC)

[edit] Why Bicarbonate?

Why is it called sodium bicarbonate when there are no two's in the formula anywhere? My chem professor just started teaching inorganic nomenclature and he doesn't even know. The Ungovernable Force 05:02, 17 February 2006 (UTC)

The article for bicarbonate states "A Bicarbonate or, more properly, a hydrogen carbonate is a polyatomic ion whose formula is HCO3." and "Bicarbonates are more correctly named hydrogen carbonates in the chemical nomenclature system." PrometheusX303 15:01, 1 March 2006 (UTC)
In older days, the prefix bi (when used in chemistry) meant hydrogen, not the number 2 as it usually means. So by this older style of nomenclature, sodium bicarbonate = Na[sodium] H[bi] CO3[carbonate]. 220.235.240.56 14:03, 21 April 2006 (UTC)
I never heard of this... always thought it came in analogy (in a way erroneously) from the higher oxidized metals: CaCO3 = calcium carbonate, Ca(HCO3)2 = calcium bicarbonate. Mattert 14:53, 12 August 2006 (UTC)

You never heard of that becuase it's utter garbage. The prefix "bi" has always meant "2". As you suggest, it refers to the fact that, per sodium atom, sodium bicarbonate has twice as much carbonate as does sodium carbonate. I suspect it stems from very early chemistry, when some atomic weights were only known to within a factor of a small integer. If it was thought that the atomic weight of sodium was 46, then "sodium carbonate" would be "NaCO3", and sodium bicarbonate would be "Na(HCO3)2", presumably from the amount of CO2 that's generated by heating a certain mass of the salt. It's unclear to me whether those who first studied it, not having the same understanding of valence and bonding that we do, understood that there was an H in bicarbonate, so they may have actually thought that sodium bicarbonate was somehow "Na(CO3)2", again with the putative Na atom of weight 46. It wouldn't surprise me that their experiments weren't precise enough to see the weight difference between Na(CO3)2 and Na(HCO3)2. It was only after the actual formula was determined and the name stuck, that "bi" came to mean "hydrogen".

[edit] Nomenclature

The prefix bi is very common when referring to acid salts in the older nomenclature; sodium bicarbonate is sodium hydrogen carbonate, sodium bisulfate is sodium hydrogen sulphate and ammonium bifluoride is ammonium hydrogen fluoride.

Socksysquirrel 00:04, 29 April 2007 (UTC)


I think that the title of the article should be changed to Sodium hydrogen carbonate, since that is the more correct name. Owen214 03:17, 6 November 2006 (UTC)
I read that it's called "bi" because the HCO3- molecyle has the ability to react both as acid and base (an ampholyte) Teol 18:38, 3 March 2007

[edit] Nasty

Add to hair if it's dirty and there's no time to wash it. Dry with warm air.

Who wrote this?

This is a known use. I've seen mentions of it in over a dozen camping, outdoor living and survival books. I think it's even listed in an 80s edition of the Boy Scout Handbook. Once, when I was camping in an arid region for two weeks, I did it myself. It doesn't clean your hair, but it makes it a heck of a lot less greasy. Supposedly the baking soda adsorbs oil and skin flakes from the hair and scalp. When you shake or brush it out, the baking soda falls out, with the oil and skin cells attached. Unless your hair's wet, most of it falls out. Now, with that said, this use isn't THAT common, so I think whoever added this tip was thinking of another use: While washing your hair (with water) you rub a paste of baking soda into your scalp to remove dandruff as an alternative to coal tar or pyridine zinc, I think it is. This is a much more common use. 68.119.223.51 09:30, 11 June 2007 (UTC)

[edit] Decomposition of Sodium Bicarbonate

In my AP Chemistry class, we have learned that the decomposition of such a compound will produce three products: The metal oxide (NaO), carbon dioxide gas (CO2), and gaseous water (H20); however, this article states that NaHCO3 will decompose into NaCO3, liquid water, and carbon dioxide gas.

How is this discrepancy explained? ...The only problem I see is that the article states that this decomposition will take place at 60 degrees Centigrade, and water will not boil at that low of a temperature. Am I to assume that the method we have learned in class assumes the reaction is taking place at a higher temperature that will not only boil the water but also decompose the Sodium Carbonate as well into its constituent elements of Sodium Oxide and Carbon Dioxide?

--Matthew Wilson 15:11, 12 March 2006 (UTC)

I think it really depends on how you decompose it. I know that adding NaO to water and mixing in CO2 will give you NaHCO3, but I dunno how to go backwards. I don't think the article as it stands is correct. I'll need to do some research before changing it, though. --M1ss1ontomars2k4 (T | C | @) 23:56, 1 June 2006 (UTC)

This is explained by NaCO3 -> NaO + CO2, further breakdown depending on conditions.

--User:algolo 23:21, 19 September 2006

check out this msds (specially melting point) it´s in spanish but i think you can manage it

http://chemdat.merck.de/documents/sds/emd/esp/es/1063/106329.pdf

Not all carbonates decompose on melting to form metal oxides. The Alkali Metal Carbonates simply melt on heating which is quite useful in chemistry. According to the German Wikipedia article Na2CO3 melts at 853 °C where it is quite stable. A decomposition at very very hight temperatures was frequently discussed (and is maybe somewhat likely), however I'd say you need some 2000 °C for this. Didn't try, found no trustworthy source. However, NaHCO3 easily decomposes to Na2CO3, Water and Carbon Dioxide. Vytas, 155.56.68.220 09:39, 27 February 2007 (UTC)

[edit] Chemical Database Fix

I fixed the Hazardous Chamical Database link at the bottom of the properties page. - Xaro

[edit] The table image.

If someone could make a new image it would be much appreciated, this one looks terrible when its enlarged. Ryan Jones 12:40, 8 April 2006 (UTC)

Done. Jesse 06:01, 8 July 2006 (UTC)
I stuck the pH in the article... why isn't pH in the table? I've noticed its lack in other chemicals... but the reason I came to this article was to find out the difference in alkine between baking soda and washing soda. I'd rather the pH wasn't in the middle of the article but rather in the table, since it's an important property and non-chemists won't look at the formula and be able to deduce it. (Gaviidae) 82.93.133.130 15:17, 2 January 2007 (UTC)

[edit] Added citation

Found this: After absorption the alkali carbonates increase the alkalinity of the tissues, and there is an increased excretion of urine, which is rendered less acid. The carbonates are largely employed in medicine with the object of retaining uric acid in solution in the urinary passages; they are of no value for dissolving uric acid already precipitated, but they form a means of preventing further precipitation.[1], dunno if it should be in the article but added the link for the ambiguous "cleans the kidneys" line. Gaviidae 11:06, 29 June 2006 (UTC)

Heck, at least half of the Uses section should go altogether. Baking soda may have "over a hundred uses", but this article isn't a how-to guide, we don't need to list them all. At least, the established industrial uses with encyclopedic verifiability should be kept strictly separate, and the folk medicine and household witchcraft get their own section, if any. Femto 12:01, 1 July 2006 (UTC)

[edit] This is Just a Stub

Why don't some of you chemists out there tell us how Baking Soda/sodium bicoarbonate is made, where it comes from, who discovered it? Duh! Scott Adler 22:45, 4 August 2006 (UTC)

We will - but there are a lot of pages to write, and only a few busy chemists....! Walkerma 00:35, 12 August 2006 (UTC)

[edit] Wheres the carbon?

Where is the carbon in the bond diagram of the molecule???--Light current 17:40, 11 August 2006 (UTC)

For some reason the person drew this in line-angle formula style, which is the default in most molecule editors. Normally it's just used for organic compounds. The carbon is at the junction of the lines. I'll try to put something better up when I get a few minutes. Thanks, Walkerma 00:37, 12 August 2006 (UTC)
Im not a chemist but thanks--Light current 04:43, 12 August 2006 (UTC)
The carbon just magically appeared! Walkerma 05:16, 12 August 2006 (UTC)

[edit] Naming

Should this article be moved to Sodium hydrogen carbonate, with Sodium Bicarbonate as a redirect? After all, the bi- prefix is now depriciated, and SHC is the only name I've seen in scientific/engineering contexts. Admittedly, Bicarb is the more commonly known name, but most other chemical articles (Acetic acid, sulfuric acid, aluminium oxide) use the IUPAC recommended name. I'd also like to see the other bicarbonates (Potassium bicarbonate, Calcium bicarbonate, Ammonium bicarbonate) move accordingly ideally. Laïka 14:55, 16 October 2006 (UTC)

[edit] Baking soda

Isn't this substance used to make crack cocaine? mirageinred 23:08, 20 October 2006 (UTC)

Yes, not having made it though. My understanding is that cocaine is provided as a hydrochloride salt, meaning that it is acidic and not very volatile. Treatment with bicarb converts the hydrochloride to "free base", which is volatile (like a most smallish organic compounds).--Smokefoot 23:27, 20 October 2006 (UTC)
It makes it freebase, which is smokeable, but the hydrochloride is not that acidic and is snortable. for pure freebase you need to dissolve it in ether and siphon off the other shit then evaporate the ether (don't make crack it screws you up). —Preceding unsigned comment added by The Right Honourable (talk • contribs) 00:20, 1 September 2007 (UTC)

[edit] Advice sought: What to do with long list of domestic uses (and legends)?

WE-Chem needs to think about how to proceed with this article. Probably others have dealt with similar issues on comparable pages. This article is evolving from an encyclopedia article into a "laundry list" of advice and lore. We could:

  • 1) contract all the domestic uses, summarizing with the statement that "NaHCO3 has many domestic uses in cleaning and cooking."
  • 2) start a page on "Domestic uses of sodium bicarbonate." and dump all the stuff there.
  • 3) try to prune these entries as they come in.

Overall, few of the domestic claims could be verify/documented. And even if they could, such applications might seem peripheral to the article. Although I am inclined toward option 1, other voices should be heard. --Smokefoot 18:38, 22 October 2006 (UTC)

I feel like option 2 .. if the domestic uses article does not get much positive attention, one could think about an AfD, or maybe, even do that directly. The NaCl article has quite a nice solution, I think. --Dirk Beetstra T C 18:51, 22 October 2006 (UTC)
It probably doesn't help the situation any, but I added a "Disputed" tag to that section. It really bothers me to see a lot of unsupported old wives tales there. Although many of the things there may be true, they aren't backed up by anything. I feel a fair number of those uses should be there, but they really need to be backed up by documentation. Even despite [[2]], I've heard that using it in the fridge is of little use, for instance. --Mdwyer 19:58, 10 December 2006 (UTC)
I think Smokefoot's suggestion above is a good one - we should do all of the above. This is rather like trivia/mentions in pop songs or films/famous people from X sections - they tend to grow out of all proportion to their importance (see Steve Biko for an example). I will commit to working on this article over the Christmas break, and I will spin most of them off into a separate article which will demand a citation for every claim. I have a couple of books which I can cite for at least some of the uses, that will at least make the "domestic uses" page more encyclopedic. My main goal will make it easier to clear stuff from this page when people begin to add "It is used on poodles to keep their coats clean" etc. etc. Walkerma 03:13, 11 December 2006 (UTC)
Without any specific examples the disputed tag is highly disingenuous. --Belg4mit 23:56, 19 May 2007 (UTC)
Moving these claims elsewhere seems like overkill, and detracts from the page. First, this isn't that lengthy of an article. Second, do any of you REALLY think most people who navigate to this article are looking up the substance's history, production or chemical properties? I seriously doubt it. They're looking for these uses. Most of the domestic uses in this article are widely-known claims by the Arm & Hammer Company (a division of Church & Dwight) . Most of the claims in this article, are listed on their website. Yes, they may not be scientifically verified, but when you think about it, they probably never will be. If scientists stopped working on vaccines to study consumer baking soda benefits, people would get incredibly upset. Still, most of these claims have nearly 100 years of anecdotal evidence backing them up, thus they constitute generally accepted common knowledge. Why not just list the most common claims that are referenced on Arm & Hammer's web site in a domestic uses section at the bottom of the article? Then, simply put any unlisted/dubious uses in a subsection with citation needed tags? Moving useful info that is probably the main reason for visits to this article takes away from its usefulness, and makes it only useful to chemists and 6th-grade kids doing reports on acid-base reactions. 68.119.223.51 09:20, 11 June 2007 (UTC)
Interesting. I came to this page because I trust the anecdotal claims on the Arm and Hammer website not as far as I can throw one. As a cleaning agent in a laundry detergent, what interactions are there between baking soda and the dyes (or other colorants) used in textiles? Is it completely colour fast? Gets your whites, white. Gets your colours white. Gets your blacks white, too. Who knows? All the anecdotes I found focus on its cleaning power. MaxEnt 03:20, 29 July 2007 (UTC)

I agree that domestic uses are a common draw to this article, however, more I feel that more elaboration and citation is needed, hence a new article for said uses may be in order. I would specifically like to know the mechanism that allows bicarb to deodorize.

Air deodorization is supposedly through adsorption, however given the relatively small surface area of sodium bicarb as opposed to active carbon, it's not really that effective. For laundry deodorizing, it's also not really effective. It's most likely the detergent's action of breaking down organic compounds that does the job. 97.82.247.200 10:18, 21 September 2007 (UTC)

[edit] pH 8.3?

In the article you can read that NaHCO3 is a salt with a pH of 8.3, leaving a reference to what seems like a rather unchemical article. A salt cannot have a pH in itself, only its solution in water can, and the actual pH value will then depend on the concentration. I'm not a chemist myself, but could it be that the author has mixed up pH with pKa? HymylyT@C 16:04, 4 February 2007 (UTC)

Agreed. Is there someway that you would fix that? Remove the pH entirely? --Mdwyer 18:42, 4 February 2007 (UTC)
I'd say leave in the ph, but add a line for the pKa. Though it may be technically wrong, ph is still useful to students trying to understand where the item itself falls on the ph scale in relation to other chemicals of known ph. 97.82.254.213 21:21, 27 June 2007 (UTC)

--EatingSteak 18:42, 16 July 2007 (UTC)

I am a Chemical Engineer, albeit somewhat rusty at these particular mechanics. However, I do agree that a pKa would be more appropriate here (or should it be pKb?). Anyway, I have commonly seen pH values associated with salts and other compounds. While this might not be quite correct, it may refer to something obscure, like "the pH of a saturated solution of this substance", hence implying a minimum or maximum pH it can have, giving the number some sort of scientific meaning. If anyone can expand on that or back me up, then do so by all means.

Under the "Chemistry" section, the article says, "[sodium bicarbonate] has a pKa of 6.3 in water which causes aqueous solutions to be mildly alkaline." This is not true. The pKa of bicarbonate ion is around 10.25. I know this from experience, but it is also found on the carbonic acid page. The 6.3 number is the so-called "acidity constant of carbon dioxide." The pKa of carbonic acid is formally 3.60. Since carbonic acid is always in equilibrium with CO2 and water, the pKa of carbonic acid in practice is 6.36. Regarding the other stuff about pH, it only makes sense to specify pH of a solution, since pH is a measure of H3O+ concentration.12.219.209.243 (talk) 01:29, 19 November 2007 (UTC)

[edit] Rxn with citric acid

I was hoping someone could help me with a question. In doing a simple experiment to show that lemon juice(citric acid) added to the sodium bicarbonate you get the same reaction of bubbling water as when you use vinegar(acetic acid). I understand now, chemically why this is but am missing 2 pieces to my puzzle.

1. what does the chemical reaction between the NaHCO3 and the C6H8O7  look like to show its by products?

2. I concluded that the reason the lemon juice(citric acid) seemed to actually work better was because the molecule contained More C, H, and O than the acetic acid does leading to the production of more water & CO2 as by products. Is this conclusion generally correct? I appreciate the help.Imnoxprt 12:44, 9 February 2007 (UTC)Imnoxprt

Citric acid is a polyprotic acid, meaning one molecule donates more then one hydronium ion (H+) to solution. Each molecule of citric acid contains three carboxyl groups (COOH) and can donate three hydronium ions. Acetic acid only contains one carboxyl group and can only donate one hydronium ion to solution. As a result three times the moles of acetic acid would be required to produce the same quanity of CO2 as citric acid. The overall reactions will cirtic acid would be:

3NaHCO3 + C6H8O7 --> 3H2CO3 + C6H5O7Na3 Where acetic acid would be: 3NaHCO3 + 3C2H4O2 --> 3H2CO3 + 3C2H3O7Na Carbonic acid (H2CO3)then produces CO2, which are the bubbles you see. H2CO3 --> H2O + CO2 --158.57.45.246 16:29, 23 February 2007 (UTC)

Hydronium is H3O, not H+. Hydronium is only formed after the acid has donated the hydrogen ion to a water molecule. --70.127.201.86 02:02, 4 May 2007 (UTC)

[edit] Use in pretzels

I deleted the following sentence because according to Pretzel, it is Sodium Carbonate, not Sodium Bicarbonate, which is sometimes used in pretzels: "* Sodium bicarbonate is used to give pretzels their dark brown color.[citation needed]" --Trbdavies

[edit] Air freshener

According to this video: [3], you can put 1/4 cup of baking soda in a spray bottle, fill it with water and use it as an air freshener. —Preceding unsigned comment added by Contralya (talk • contribs) 18:54, 4 May 2008 (UTC)