I have really tried to figure this out for myself. Please I am embarrassed to even ask, but I don't understand some important rule for naming
compounds. For example, why is sodium bicarbonate the name for NaHCO3? I am confused because it would seem that sodium bicarbonate would be Na(CO3)2.
I realize Na(CO3)2 doesn't make sense because the valence doesn't work out. It would have to be Na2CO3. But that name would be bisodium carbonate. Bot0nist - 25-9-2013 at 11:49
Dont feel bad. The older names are confusing. Check into IUPAC names. It is much more umm logical, as far as I can tell.DraconicAcid - 25-9-2013 at 12:20
The reason that the old name for sodium hydrogen carbonate is sodium bicarbonate is because, as they noted long ago, sodium carbonate (Na2CO3) is
43.4% sodium and 56.6% carbonate (1.3 g carbonate for every 1 g of sodium). Sodium hydrogen carbonate (NaHCO3) is 21.5% sodium and 56.1% carbonate
(2.6 g of carbonate for every 1 g of sodium). Since the latter contains twice as much carbonate (per sodium) as the former, the name "bicarbonate"
makes sense, particularly back in the days when they were still working out chemical formulas.Mesa - 25-9-2013 at 12:24
In addition to what Bot0nist said, the study of the history of words is called "etymology." I don't doubt that you have spent a substantial amount of
time using search engines to figure out the answer to your question, sometimes(most of the time) you just need to know that one keyword that will give
you exactly the answer you need.
Although, after reading it I find myself more confused than when I started.
very helpful
quantumchromodynamics - 25-9-2013 at 23:55
Thanks very helpfulFantasma4500 - 26-9-2013 at 02:08
my teacher corrected me when i said 'copper dichloride' apparently CuCl2 is referred to as just copper chloride, i guess because CuCl is more seldom
than CuCl2, even CuCl4 exists by what i know but its more unstable than CuCl by what i understand
i just dont hope that your first language isnt english, because thats more than just frustrating when trying to figure out chemistry and translations
and all12AX7 - 26-9-2013 at 04:07
Just to throw confusion to the wind,
Note that potassium chromate is K2CrO4, while the dichromate is K2Cr2O7. If you were careless in your work, you might incorrectly assay the
dichromate as KHCrO4 (say by not drying it thoroughly: H2O + K2Cr2O7 = "2 KHCrO4"), which would be a bichromate -- which doesn't actually exist.
By the way, similar analogies can be made with sodium bicarbonate (2 NaHCO3 = "H2O + Na2C2O5", which doesn't exist -- CO2 is lost along with the H2O)
and sodium bisulfate (in which case, the anhydrite actually exists: 2 NaHSO4 = H2O + Na2S2O7, sodium pyrosulfate -- which presumably could also be
called the disulfate!).
Tim
[Edited on 9-26-2013 by 12AX7]DraconicAcid - 26-9-2013 at 08:34
my teacher corrected me when i said 'copper dichloride' apparently CuCl2 is referred to as just copper chloride, i guess because CuCl is more seldom
than CuCl2, even CuCl4 exists by what i know but its more unstable than CuCl by what i understand
You wouldn't call it copper dichloride, because you don't generally use Greek prefixes for ionic compounds. You can call them "cupric chloride" and
"cuprous chloride" if you want to be old-fashioned, or "copper(II) chloride" and "copper(I) chloride" if you want to be understood, but any dichloride
would be a molecular compound (sulphur dichloride, selenium dichloride, etc.).
You may see older books ignoring this, but that won't be the nomenclature your teacher is trying to teach you. (I just spent 5 minutes yelling at my
class for googling up trivial names for their nomenclature assignment instead of coming up with the systematic names following the rules they were
supposed to have learned.)
