Acid salts

   
 
What are they?  |  How are they named? If we know the formula  | If we know the name  |  Examples  |  IUPAC systematic nomenclatureExercises
   

What are they?

The oxyacids with several hydrogens can form salts with acid hydrogens.

How are they named?

    It was named as the neutral salts with prefixes hydrogen- or dihydrogen- front of the name of neutral salt.

If we know the formula

    In the formula:   NaHCO3

a) Separate from the salt cation and anion

Deduces the charge of the anion (negative ion) from the charge of the cation (positive ion)

b) Deduces the oxidation number of the central atom, knowing that the oxygen has oxidation number -2 and hydrogen +1.

c) Recalls oxidation numbers of central element, and writes the prefixes and suffixes.

The first word is the name of the metal, followed immediately by the oxidation number between brackets and in Roman numbers. If the oxidation number of the metal is invariable, it is not indicated. The second word is the name of the anion with the prefixes hydrogen- or dihydrogen-.

If we know the name

    In the name: Sodium hydrogensulfite

a) Write the symbol of the cation with its electrical charge. Based on the prefixes and suffixes deduces the number of oxidation central element involved in the anion:

b) Formulates the oxyacid of S+4

c) Deduces the anion from the acid. The anion has so many negative electrical charges as hydrogens loses the acid. Calculate the fewest ions of each type that you need so that the compound be neutral.

 

Examples

 

  Cation Anion

Name

NaHCO3 Na+ HCO3- Sodium hydrogencarbonate
Fe(HSO4)3 Fe+3 HSO4- Iron(III) hydrogensulfate
Ca(HSO3)2 Ca+2 HSO3- Calcium hydrogensulfite
Ca(H2PO4)2 Ca+2 H2PO4- Calcium dihydrogenphosphate
K2HPO4 K+ HPO4-2 Potassium hydrogenphosphate

 

IUPAC systematic nomenclature

     As in oxyacids we use two nomenclatures: is the additive names and the stoichiometric names.

      The additive names for anions: are based on the structure of the anions, 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 finished in –ate, followed by the charge number, with a minus sign, between brackets. (Ewens-Bassett's system)

      The stoichiometric names for anions: are formed by the word "hydrogen" with the prefix that shows us the number of atoms of hydrogen and  the word "oxido" with the prefix that shows us the number of atoms of oxygen, followed by the central atom finished in –ate, followed by the charge number, with a minus sign, between brackets. (Ewens-Bassett's system)

Anion

Additive names

Stoichiometric names

 HCO3-  Hydroxidodioxidocarbonate(1-)  Hydrogentrioxidocarbonate(1-)
 H2PO4-  Dihydroxidodioxidophosphate(1-)  Dihydrogentrioxidophosphate(1-)
 HPO42-  Hydroxidotrioxidophosphate(2-)  Hydrogentetraoxidophosphate(2-)
 HSO3-  Hydroxidodioxidosulfate(1-)  Hydrogentrioxidosulfate(1-)
 HSO4-  Hydroxidotrioxidosulfate(1-)  Hydrogentetraoxidosulfate(1-)
 HSeO3-  Hydroxidodioxidoseleniate(1-)  Hydrogentrioxidoseleniate(1-)
 HSeO4-  Hydroxidotrioxidoseleniate(1-)  Hydrogentetraoxidoseleniate(1-)

       The additive names for salts: Write the name of the cation followed by the name of the anion, with the charge ( Ewens-Bassett's system) in cantions having no fixed oxidation number.

      The stoichiometric names for salts: Write the name of the cation, with the prefixes di-, tri-, tetra-, etc. we suggest repetition of the cation. Following the anion without the charge, if necessary with a prefix, tris, tetrakis, pentakis, hexakis, etc. tell us that the repetition of anion.

Salt

Additive names

Stoichiometric names

 NaHCO3  Sodium hydroxidodioxidocarbonate(1-) Sodium hydrogentrioxidocarbonate
 Ca(H2PO4)2  Calcium dihydroxidodioxidophosphate(1-) Calcium bis(dihydrogentrioxidophosphate)
 K2HPO4  Potassium hydroxidotrioxidophosphate(2-) Dipotassium  hydrogentetraoxidophosphate
 Fe(HSO3)2  Iron(II) hydroxidodioxidosulfate(1-) Iron bis(hydrogentrioxidosulfate)
 AgHSO4  Silver hydroxidotrioxidosulfate(1-) Silver hydrogentetraoxidosulfate
 Ba(HSeO3)2  Barium hydroxidodioxidoseleniate(1-) Barium bis(hydrogentrioxidoseleniate)
 Fe(HSeO4)3  Iron(III) hydroxidotrioxidoseleniate(1-) Iron tris(hydrogentetraoxidoseleniate)

 

Exercises

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.

Formulae 1 Names 1 Formulae 2 Names 2 IUPAC Formulae 1 IUPAC Names1 IUPAC Formulae 2 IUPAC Names2

 
   

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