Talk:Strong acid

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Why is this a separate article from acid, please? And why do we need a separate article for "strong base" when we don't have any article yet for base? Giving "acid" two articles and "base" none doesn't seem very NPOV, if you know what I mean. -- isis 18:25 Oct 26, 2002 (UTC)
 * There is an article called Base (chemistry), so named to distinguish it from other base articles. There is also an article on strong base.  H Padleckas 11:15, 4 Apr 2005 (UTC)

We of the Holy Brotherhood of the Acidic Order find this skewing toward a pro-base viewpoint very disturbing. (yeah, probably merge)-- Tarquin 19:59 Oct 26, 2002 (UTC)

Is the rehash definition of pH truly necessary on this page? It seems more like an aside. After all, there is a link to it in the sidebar, for those who truly need it. --Kinu 19:52, 9 February 2006 (UTC)


 * I agree. I'd suggest wiping out that paragraph, and wikifying pH where it occurs later in the article.  Csari 21:42, 9 February 2006 (UTC)

I'm going to reiterate the 2002 consideration: 95% of the content here is also on acid, and the rest could be incorporated into acid. If no one objects in the next month, I'll probably do it. Olin 22:08, 2 March 2006 (UTC)

If a merger is going to take place in the near furture, then the following change doesn't really have a great deal of significance, but I'm going to make it anyway. According to "General Chemistry 4th ed." by Hill, et al., the strong binary acids of group 7 (specifically, HCl, HBr, and HI) are all stronger than the polyprotic acid H2SO4. Furthermore, the Wikipedia entires on those acids agree, as well as other websites. Consequently, I am going to make the appropriate changes in order, and cite my textbook as a reference. Firewall62 23:20, 4 March 2006 (UTC) I would just like to note that strength of acid refers to pKa (or Ka), not pH. Sulfuric acid has a lower pH than HCl because it is diprotic, but has a higher pKa.

In order to be a strong acid proper, the pKa MUST be less than -1.74, that of hyronium, the protonated solvent. See Talk: Inorganic nonaqueous solvent for more. -User: Nightvid

Order?
The order is supposedly strongest to weakest, but according to the entries for HI, HBr, and HClO4, the order is wrong - HClO4 is last among the three and I am editing the article accordingly. Ataru 03:26, 7 August 2006 (UTC) Could someone find the pKa for perchloric acid from a reliable source? The pKa article on wikipedia gives it at -10, but the percholrous acid article on wikipedia gives it as -7 (and reference it to a source that has a disclaimer saying that -7 is prob inaccurate). I have a feeling that perchloric acid is stronger than HCl, contray to previous edits, because perchloric acid's conjugate base should be more stable in solution than Cl-, in a similar way to I- being more stable then Cl- (it will have a more even distribution of charge, less likely to attract the H+ ion again, so dissociates better). My text book Chemistry 8th Edition by Chang lists perchloric acid as stronger than any of the hydrogen halides.

Also, some one has added HF to the extremely strong acids list. I will remove, as this is obviously wrong.

The name and formula for HI and HBr seems to be interchanged. Which one come first?

What concentration is being used to determine the "weakest to strongest" order of these acids? 63.225.174.209 03:48, 4 July 2006 (UTC)

And shouldn't the hydronium ion be removed from the list? It's not an acid in any sense of the word. 63.225.174.209 03:51, 4 July 2006 (UTC)

Hydronium Ion is an acid, in every sense of the word. Bronsted definition: proton donor. In reactions with for example OH, it forms 2 H20, acting as a proton donor. Just because the hydronium ion is not as strong an acid as say HCl, doesn't mean it's not an acid. Hydronium ion is stronger acid than acetic acid and many others.

From the "Acid" page: "That approximates the modern definition of Brønsted and Lowry, who defined an acid as a compound which donates a hydrogen ion (H+) to another compound (called a base)." Acids are compounds. The hydronium ion is not a compound. The hydronium ion is not an acid. 63.225.175.108 21:34, 17 October 2006 (UTC)

There seems to be some misconceptions here, and some things in the article that while true may lead some people to draw the wrong conclusions. Here are my two cents:

1) Hydronium ion is an acid and is a compound. it is the conjugate acid of water.

2) Listing hydronium ion on the list of strong acids is odd, since the definition of strong acid is a protic acid that completely dissociates in water, but the dissociation is often written with hydronium as a product (obviously the proton is labile and moving around, but hydronium isn't "completely dissociated).

3) since pKa is the pH at which a protic acid is 50% ionized at equilibrium, having a pKa just a little less than hydronium isn't sufficient for it to be called a strong acid. (But this is a moot point since I don't think any protic acids are known which fall in this category.)

4) Don't spend too much time arguing about the correct order of the strength of the strong acids. The pKa's in water of the strong acids are theoretical estimates, which vary depending on how they are measured or computed.  (Obviously they can't be measured directly since the acids are completely dissociated).

5) I think the list of almost strong acids is superfluous (what would the cutoff point be? I can think of many more which are pretty strong, but I wouldn't add them.). Stick to the main six and the superacids.     63.99.16.91 21:36, 1 December 2006 (UTC)


 * Yeah, the order is ridiculous because it's very difficult to verify which one is the strongest. I have found 3 different values of pKa of nitric acid from 3 different sources (-1.3 ; -1.44 ; -1.5 and -2 in Wiki). Moreover, should we add some more like HCOOH and H2C2O4 because they're really popular (much rather than one like HFSbF5). Causesobad --> Talk) 14:23, 22 January 2007 (UTC)


 * formic acid and oxalic acid are not strong acids (magic acid is). Also, I will fix this article when I have time. 208.4.152.131 22:19, 5 February 2007 (UTC)

Throwing in my university chem book, the strength of some acid (in decreasing order): But even the book itself has some contradicting numbers. OhanaUnited  20:34, 6 April 2007 (UTC)
 * Iodic acid: HIO3
 * Chlorous acid: HClO2
 * Nitrous acid: HNO2
 * Sulfric acid: H2SO4 (first step)

Sulfuric acid should be above hydrochloric acid in the order of strengths though as sulfuric acid will displace chlorine from its salts, forming hydrochloric acid and the metal sulfate.


 * Assuming the previous unsigned commenter means aqueous solutions, this depends on solubility only. For barium, sulphate and HCl will be formed, for silver - chloride and sulphuric acid. (and, for the record, I don't see a point specifying any kind of order for strong acids in water) Cubbi 23:40, 6 May 2007 (UTC)

H3O inclusion
I'm going to edit out the incorrect sentence about oxygen having a formal charge of +1 in H3O. But I think the hydronium ion should be removed from the strong acid list entirely because most definitions of strong acid rely on the qualitative Arrhenius definition that a strong acid fully is an acid that completely dissociates in water. H3O is the zero between strong and weak. aevea (talk) 06:29, 2 February 2009 (UTC)