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What are they? |
How are they named? | If we
know the formula | If we know the name
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Examples |
IUPAC systematic nomenclature |
Exercises |
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What are they?
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They are called oxyacids, and have
a general formula:
HaXbOc
X is usually a nonmetal, but can be a transition metal in a
high number oxidation, as Cr+6, Mn+6 or Mn+7.
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How are they named?
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The IUPAC supports common nomenclature in this kind of compounds.
Common nomenclature.
To formulate these compounds need to know the oxidation numbers of nonmetal X.
They are as follows
| Halogens
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+1,
+3, +5, +7
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| Chalcogens |
+4,
+6
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| Group
of N
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+3,
+5
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| Group
of C |
+4
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In the acid formula deduce the oxidation
number of element X (+ n) shall be equal to twice oxygens minus hydrogens. The
result is divided by the number of atoms X.
The oxidation number of X shown by some prefixes and suffixes.
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Oxidation
numbers
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Acid
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Highest
High
Low
Lowest
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per-
-ic
-ic
-ous
hypo-
-ous
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If we know the formula
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In the formula: Deduce the oxidation number of the
central element, as we saw it twice oxygens
minus hydrogens, and as (highest, high, low or lowest) we
termination appropriate (per- -ic,
-ic, ous- or hypo-
-ous).
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If we know the name
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In the name:
Based on the prefixes and suffixes deduce the oxidation
number of the central element. Hydrogen oxidation number
+1 and oxygen -2. We look after coefficients so that the
charge provided by the oxygens is equal and
opposite to that provided by the hydrogens and the central element.
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Examples
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The most common oxyacids are:
HALOGENS:
oxidation numbers:
+1, +3, +5, +7.
Oxyacids form the Cl, Br, and I, but not the F.
| Oxidation
Number (+1): HClO
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hypochlorous
acid |
| ON (+3): HClO2
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chlorous
acid |
| ON (+5): HClO3 |
chloric
acid |
| ON (+7): HClO4
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perchloric
acid |
CHALCOGENS:
oxidation numbers:
+4, +6. Oxyacids
of S, Se, Te.
| ON (+4): H2SO3
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sulfurous
acid |
| ON (+6): H2SO4
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sulfuric
acid |
GROUP OF N: oxidation
numbers:
+3, +5. Oxyacids of N, P, As.
| ON (+3): HNO2 |
nitrous
acid |
| ON (+5): HNO3 |
nitric
acid |
| Also known N+1
:H2N2O2 |
diazenediol |
The oxyacids of P and As are 3 hydrogens.
| ON (+3): H3PO3
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phosphorous
acid |
| ON (+5): H3PO4 |
phosphoric
acid |
CARBON AND SILICON: oxidation
number: +4.
| ON (+4): H2CO3 |
carbonic
acid |
| ON (+4): (H2SiO3)n |
metasilicic
acid |
| ON (+4): H4SiO4 |
silicic
acid |
CHROMIUM AND MANGANESE:
Also forming acids that transition metals, for example, Cr and Mn.
| ON (+6): H2CrO4 |
chromic
acid |
| ON (+6): H2Cr2O7 |
dichromic
acid |
| ON (+6): H2MnO4 |
manganic
acid |
| ON (+7): HMnO4 |
permanganic
acid |
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IUPAC systematic
nomenclature
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For oxyacids IUPAC proposed
two nomenclatures, in addition to admit as valid common names, is the additive
names and the hydrogen names.
The additive names
are based on the structure of the acid, naming differently the oxygen that are
tied to the acid hydrogens (hydroxido), and the oxygen only united central
element (oxido). These names carry prefixes corresponding di-, tri-,
tetra- and so on. And are named in alphabetical order followed by the name of
the central atom.
Prefix-hydroxido-prefix-oxido-CENTRAL ELEMENT
The hydrogen names
are formed by the word "hydrogen" with the prefix that shows us the
number of atoms of hydrogen, between brackets the word "oxido" with the
prefix that shows us the number of atoms of oxygen, followed by the central
atom finished -ate.
Prefix-hydrogen(Prefix-oxido-CENTRAL ELEMENT-ate)
| Formula |
Structural formula |
Additive names
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Hydrogen names
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| HClO |
Cl(OH) |
hydroxidochlorine |
hydrogen(oxidochlorate) |
| HClO2 |
ClO(OH) |
hydroxidooxidochlorine |
hydrogen(dioxidochlorate) |
| HClO3 |
ClO2(OH) |
hydroxidodioxidochlorine |
hydrogen(trioxidochlorate) |
| HClO4 |
ClO3(OH) |
hydroxidotrioxidochlorine |
hydrogen(tetraoxidochlorate) |
| H2SO3 |
SO(OH)2 |
dihydroxidooxidosulfur |
dihydrogen(trioxidosulfate) |
| H2SO4 |
SO2(OH)2 |
dihydroxidodioxidosulfur |
dihydrogen(tetraoxidosulfate) |
| HNO2 |
NO(OH) |
hydroxidooxidonitrogen |
hydrogen(dioxidonitrate) |
| HNO3 |
NO2(OH) |
hydroxidodioxidonitrogen |
hydrogen(trioxidonitrate) |
| H3PO3 |
P(OH)3 |
trihydroxidophosphorus |
trihydrogen(trioxidophosphate) |
| H3PO4 |
PO(OH)3 |
trihydroxidooxidophosphorus |
trihydrogen(tetraoxidophosphate) |
| H2CO3 |
CO(OH)2 |
dihydroxidooxidocarbon |
dihydrogen(trioxidocarbonate) |
| H4SiO4 |
Si(OH)4 |
tetrahydroxidosilicon |
tetrahydrogen(tetraoxidosilicate) |
| H2CrO4 |
CrO2(OH)2 |
dihydroxidodioxidochromium |
dihydrogen(tetraoxidochromate) |
| H2Cr2O7 |
(HO)Cr(O)2OCr(O)2(OH) |
μ-oxidobis(hydroxidodioxidochromium) |
dihydrogen(heptaoxidodichromate) |
| H2MnO4 |
MnO2(OH)2 |
dihydroxidodioxidomanganese |
dihydrogen(tetraoxidomanganate) |
| HMnO4 |
MnO3(OH) |
hydroxidotrioxidomanganese |
hydrogen(tetraoxidomanganate) |
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Exercises
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In Formulae you have an exercise to write the names of these substances
and to check your results. You also have the answer to the exercise.
In Names you have an exercise to write the formulae for these substances
and to check your results. You have to introduce the formulae without
subscripts, for example for water = H2O. You also have the answer to the
exercise.
       
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