Jump to content
Sign in to follow this  
satrohraj

-Ous and -ic ??

Recommended Posts

I always wanted to know this! :)

 

What is the real essence in saying -ous acid, -ic acid? :confused:

And, if possible i want to know, whats the difference between, ite, ate, ide, etc? :confused:

 

Thank you :rolleyes:

Share this post


Link to post
Share on other sites
I always wanted to know this! :)

 

What is the real essence in saying -ous acid, -ic acid? :confused:

And, if possible i want to know, whats the difference between, ite, ate, ide, etc? :confused:

 

Thank you :rolleyes:

 

"-ic" denotes a higher oxidation state of the ion being referred to in a compound. If you have Cupric Sulfate versus Cuprous Sulfate, then it means that the copper ion is in a higher oxidation state in Cupric Sulfate than in Cuprous Sulfate.

 

The easy way to remember this is sulfurous versus sulfuric acid. Sulfurous Acid is H2SO3 while Sulfuric Acid is H2SO4. In the "ic" acid, the sulfur atom is in an oxidation state of +6 while in Sulfurous Acid the sulfur atom is only +4.

 

"-ites" and "-ates" are pretty much the same thing as the -ous and -ic naming in acids, only these are specific to oxygen containing anions. (I.E., carbonate, nitrate, carbonite, sulfite, permanganate, etc.) The "-ate" designation means that the atom being referred to is in a higher oxidation state than the analogous "-ite" version. If you look at Nitrate (-NO3) versus Nitrite (-NO2) you'll see that the nitrogen atom in the nitrate ion is in a higher oxidation state than it is in the nitrite ion. The same with sulfate (--SO4) and sulfite (--SO3).

 

"-ide" just denotes a solitary atom with a negative charge. Hydride means a hydrogen atom with a negative charge. Sulfide is a sulfur atom with a negative charge. All of them are mononuclear ions with a negative charge. Hence why calling the f-block elements lanthanides and actinides is just plain wrong. The only acceptable naming is lanthanoids and actinoids since they are not all negatively charged ions of lanthanum and actinium.

Share this post


Link to post
Share on other sites

I got it, suppose if there is no other possible oxidation state for it, how should we name it?, ous / ic

 

Let me guess, it should be called -ous acid, right?, because there is no higher oxidation state..

 

Am I right?

Share this post


Link to post
Share on other sites

Actually, as far as I can see when there's only one possible one they are called -ic acids like carbonic boric and (a bit obscure), silicic but I don't know if there's really a good reason for this- just convention.

Share this post


Link to post
Share on other sites

What John is telling about the -ous and -ic ending is also true for -ite and -ate. When only one oxidation state is known of a compound, then the name ends in -ate, e.g. CO3(2-) is carbonate.

 

Unfortunately, in the past, numerous errors were made, in interpreting the structure of compounds and now we are left with a whole bunch of crappy names.

 

We have SO3(2-), SO4(2-) and SO5(2-). These are called sulfite, sulfate, and persulfate. This is quite OK, the SO5(2-) ion has structure [-O-O-SO(=O)2](2-). It contains two oxygen atoms in a row, and hence it is called a per-compound.

 

We also have ClO2(-), ClO3(-) and ClO4(-). Here, they are called chlorite, chlorate, and perchlorate, but here things are wrong. In fact, what is called perchlorate, could better be called chlorate, because it is the highest oxidation state for chlorine (+7) and there is no peroxo-group in this ion.

 

So, for the most common ions, it is best to simply learn these things.

 

For the more special things, the IUPAC naming convention is used more and more, which is unambiguous, but unfortunately also somewhat awkward.

 

http://www.iupac.org/reports/provisional/abstract04/connelly_310804.html

Share this post


Link to post
Share on other sites

Please keep in mind that this is a forum. Of course, jdurg may give you his address, if he wishes and you may have private communication, but I personally think you will have more response by using the public forums.

 

But if you want to contact any person in a private way, just send a PM (click the private messages link at the top right of the forum page). No mail needed, PM's are really private, not even I as a moderator can read other PM's than my own (the ones I received and the ones I sent), so feel safe to use PM's.

Share this post


Link to post
Share on other sites

hey Jdurg, you seem to be a chemistry expert, I may need you sometimes

can you give me your email address,

 

if you wish to give e-mail me XXXsatrohraj at gmail dot comXXX from your e-mail address!

I promise to keep it private

 

Thank you

 

EDIT by woelen: Please don't put email addresses in messages over here. John already told, but you will receive lots of spam if you do so. I changed the message.

Share this post


Link to post
Share on other sites

The spam bots have probably harvested your email by now and will send you endless trash. The PM system seems to work perfectly well so I really wouldn't recommend putting your email here.

The "lepton" thing is a light hearted way of indicating how much stuff you have posted- "leptons" haven't posted much, "quarks" a bit more and so on.

BTW, the lowest oxidation state oxy-acid derived from chlorine is hypochlorous so you end up needing lots of names and prefixes to keep track of them all. hypochlorous/ hypochlorite; chlorous/ chlorite; chloric/chlorate; perchloric perchlorate.

I personally think the IUPAC names are ugly, but I can see how they are easier to remember.

For what it's worth, the "per" in peroxide means the same as the "per" in perchlorate so the name "perchlorate" is correct. A peroxide contains "more than the usual amount of oxygen"- so does a perchlorate or a persulphate.

One could say that persulphate is wrong because it should be peroxysulphate.

HClO

Share this post


Link to post
Share on other sites
For what it's worth, the "per" in peroxide means the same as the "per" in perchlorate so the name "perchlorate" is correct.

To my understanding the "per"-prefix initially was used for peroxo-groups (-O-O-), but in those times the clear distinction between oxidation states, peroxo groups and so on was not well-developed.

 

Just to show the flawed use of "per" in many common names:

 

We have (I only draw one resonance extremum):

 

[-O-N=O](-) ---> nitrite

[-O-N(=O)2](-) ---> nitrate

[-O-O-N=O](-) ---> pernitrite

 

I made the pernitrite once. It is fairly easy, make an ice-cold solution of sodium nitrite and an ice cold solution of dilute nitric acid or sulphuric acid. Then drop ice-cold hydrogen peroxide (5% or so) in the solution. The solution turns red, but only for a short transient time. The red color is due to the pernitrite.

 

So, there are two possible ions NO3(-), with very difficult chemical properties. Using the old naming scheme both would be called nitrate.

 

So, in the sense of "more than the usual amount of oxygen", the prefix "per" would be OK, but I think that this is flawed. E.g. MnO2 is called manganese peroxide, where I live. Don't you think that is flawed? There is no peroxo group in it at all. The compound BaO2 is called barium peroxide, and that is correct, because it really contains a peroxo-group and with water it reacts to Ba(OH)2 and H2O2.

Share this post


Link to post
Share on other sites

They called high oxidation states "per" before they had any idea of the nature of the O-O bond in H2O2

The idea that it should only be used for compounds with a bond between two oxygens is relatively new. If you really want to use the new terminology then you are looking at trioxynitrate(V) for the common isomer and (I think)

oxy-peroxy-nitrate (III) for the red one.

The prefix "per" is not derived from peroxide but from Latin meaning "beyond"

Peroxides were beyond the normal oxides eg Mn and Pb (IV) oxides rather than the PbO and Mn2O3 that were normally encountered and H2O2 rather than H2O

If you wish to make the distinction then things with O-O bonds should be called "peroxy".

Share this post


Link to post
Share on other sites

Good to know that it comes from the latin word for "beyond". Although I still think some per-names are bad, I also use them, simply because everyone does.

 

If I am talking about trioxonitrate (V) and dioxonitrate(III), then most people will stare at me.... :confused:

 

Sometimes, these names are used though. I have made a complex like K3[Cr(C2O4)3] and I certainly would not call this potassium chromium oxalate, because the oxalate is really attached to the chromium. This must be called potassium tris-oxalato chromate (III).

Two other common examples are potassium hexacyanoferrate (II) and potassium hexacyanoferrate (III). So, for non-oxo anions, the use of these IUPAC names is more wide-spread.

Share this post


Link to post
Share on other sites

Most people won't have a clue what you mean if you are talking about nitrites anyway ;-)

At least most of the chemists ought to understand if you use the full IUPAC names (Though at this point I usually ask "What's the systematic name for sucrose?" and run away while people try to work it out).

Unfortunately the problem is that nomenclature has to do two opposing things- it has to uniquely identify a compound (and I think that even "potassium tris-oxalato chromate (III)" doesn't do it because there are optical isomers) but, at the same time, it has to be simple.

I doubt it's possible for it to do both so we just have to muddle along with it.

Anyway, I have to get up early so I'm off to bed.

Bye.

Share this post


Link to post
Share on other sites

if its a tertiarty acid then this applys. it ussually involves a polyatomic ion. if the polyatomic ion ends in "ate" the acid ends with "ic". if the polyatomic ion ends with an "ite" then the acid ends with "ous"

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.