Ionic Compounds
Ionic compounds are composed of cations and
anions
in the chemical formula of an ionic compound the
cation always precedes the anion
MxAy => xMy+ + yAxAl2S3 => 2M3+ + 3A2-
Electrolytes
• When ionic compounds dissolve in water the ions
separate and move independently through the
solution as aqueous ions
• Since ions are charged species their motion
through space is equivalent to an electrical
current
• It is the movement of ions in solution that is
responsible for the conduction of electrical
current in solutions
Hydration / Solvation
Ions in solution are hydrated by water molecules, a
more general term is solvated
K+ (g) + 6H2O (l) --> K(H2O)6+ (aq)
OH2
H2O
H2O
OH2
K+
OH2
H2O
1
Strong electrolytes
Strong electrolytes separate completely into ions in solution
HCl --> H+ (aq) + Cl- (aq)
NaOH --> Na+ (aq) + OH- (aq)
Weak electrolytes
Weak electrolytes separate only partially into ions in solution
HOAc --> H+ (aq) + OAc- (aq) 1%
HF ---> H+ (aq) + F- (aq) 1%
OAc- = C2H3O2- the acetate ion
Acids
Arrhenius Acids are characterized by ionizable H+
ions
These are almost always placed in the formula at
the beginning
HCl, H2SO4, H3PO4
Monoprotic, Diprotic, Triprotic, and Polyprotic
acids
Acids may have one, two, three, or more ionizable
protons
Ionization of Polyprotic Acids
H3PO4 --> H+ + H2PO4H2PO4- --> H+ + HPO42HPO42- --> H+ + PO43-
2
Strong Acids
Strong Acids ionize completely in aqueous solution
HCl --> H+ + Cl- 100%
There are seven strong acids that should be known
H2SO4, HClO4, HClO3, HNO3, HCl, HBr, HI
Weak Acids
Most other acids are weak acids and ionize only partially in aqueous
solution
HC2H3O2 --> H+(aq) + C2H3O2-(aq) 1%
H3PO4, HF, H2CO3, H3BO3
The Hydronium ion
HC2H3O2 (aq) + H2O (l) --> H3O+(aq) + C2H3O2-(aq)
H+(aq) + H2O (l) --> H3O+ (aq)
the Hydronium ion is a hydrated/solvated proton
..
H+ + : O
..
H
O
H
H
H
H
Bases
Arrhenius bases are the most well known and are those
bases which contain the hydroxide anion, OH-.
NaOH, KOH, Mg(OH)2, Ba(OH)2 and Al(OH)3 are bases
It is the OH- anion which accounts for the reactivity with
acids.
H+ + OH- ----> H2O
HCl (aq) + NaOH (aq) --> H2O(l) + NaCl(aq)
Acid + Base --> Water + Salt
3
Ammonia
A Weak Base
NH3 (aq) + H2O (l) --> NH4+ (aq) + OH- (aq) 1%
TABLE I.
Positive Ions Whose Charges Do Not Vary
___________________________________________________________________
Singly Charged, +1
Doubly Charged, +2
Triply Charged, +3
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Hydrogen,
H+
Beryllium,
Be+2
Aluminum, Al+3
Lithium
Li+
Magnesium
Mg++
Gallium Ga+3
Sodium
Na+
Calcium
Ca++
Potassium
K+
Strontium
Sr++
Rubidium
Rb+
Barium
Ba++
Cesium
Cs+
Zinc
Zn++
Silver
Ag+
Cadmium
Cd++
Ammonium NH4+
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TABLE II.
Positive Ions Having Variable Charge
________________________________________________________________________
IUPAC Name
Traditional Name
_________________________________________________________________________
Root
-ous ending
-ic ending
________________________________________________________________________________
Copper (I) and (II)
cuprCu+
Cu++
Gold (I) and (III)
aurAu+
Au3+
Mercury (I) and (II)
mercurHg+(Hg2++) Hg++
Chromium (II) and (III)
chromCr++
Cr3+
Manganese (II) and (III)
manganMn++
Mn3+
Iron (II) and (III)
ferrFe++
Fe3+
Cobalt (II) and (III)
cobaltCo++
Co3+
Nickel (II) and (III)
nickelNi++
Ni3+
Tin (II) and (IV)
stannSn++
Sn4+
++
Lead (II) and (IV)
plumbPb
Pb4+
Cerium (III) and (IV)
cerCe3+
Ce4+
Arsenic (III) and (V)
arsenAs3+
As5+
Antimony (III) and (V)antimonSb3+
Sb5+
Bismuth (III) and (V)
bismuthBi3+
Bi5+
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TABLE III
Acids which do not contain Oxygen
____________________________________________________
HF
hydrofluoric acid
HCN hydrocyanic acid
HCl
hydrochloric acid
H2S
hydrosulfuric acid
HBr
hydrobromic acid
HN3 hydrazoic acid
HI
hydroiodic acid
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Naming of Oxy Acids -ic, -ous, per-, and hypoHClO4
HClO3
HClO2
HClO
perchloric acid
chloric acid
chlorous acid
hypochlorous acid
per- means more oxygen than -ic acid
arbitrarily defined as -ic
less oxygen than the -ic acid
less oxygen than the -ous acid
The halides, Cl, Br, and I, all form four oxy acids
having the same formulas
TABLE IV
Oxy-Acids
____________________________________________________________
Formula Name
Formula
Name
____________________________________________________________
HC2H3O2 acetic acid
HBrO3
bromic acid
H3AsO4 arsenic acid
HClO4
perchloric acid
H3AsO3 arsenious acid
HClO3
chloric acid
H3BO3
boric acid
HClO2
chlorous acid
H2CO3
carbonic acid
HClO
hypochlorous acid
H2CrO4 chromic acid
HIO4
periodic acid
H2Cr2O7 dichromic acid
HIO3
Iodic acid
HOCN
cyanic acid
H2C2O4
oxalic acid
H2SO4
sulfuric acid
H2S2O3
thiosulfuric acid
H2SO3
sulfurous acid
HMnO4
permanganic acid
H3PO4
phosphoric acid H2C8H4O4 phthalic acid
H3PO3
phosphorous acid HSCN
thiocyanic acid
HNO2
nitrous acid
H4SiO4
silicic acid
HNO3
nitric acid
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5
6
Naming Salts
KCl Potassium Chloride
Na3PO4 trisodium phosphate
KH2PO4 Potassium dihydrogen phosphate
Au(NO3)3 Gold (III) trinitrate
(NH4)2SO3 Ammonium Sulfite
Ni2S3 Nickel (II) Sulfide
ANIONS NOT DERIVED FROM ACIDS
TABLE V
______________________________________________
Anion
Name
_______________________________________________
Hhydride
O2oxide
N3nitride
P3phosphide
As3arsenide
C4carbide
Si4silicide
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Binary Compounds of the non-metals
TABLE VI
___________________________________________________________________
formula Name
formula
name
___________________________________________________________________
CO
carbon monoxide
CO2
carbon dioxide
ClO chlorine monoxide
ClO2 chlorine dioxide
Cl2O7 dichlorine heptoxide
SO3
sulfur trioxide
NO
nitric oxide
N2 O
nitrous oxide
NO2 nitrogen dioxide
N2O4 dinitrogen tetroxide
PF5 phosphorus pentafluoride
PCl3 phosphorus trichloride
SF6 sulfur hexafluoride
XeF2 xenon difluoride
XeO3 xenon trioxide
S2F10 sulfur decafluoride
BH3 boron trihydride
SO2
sulfur dioxide
___________________________________________________________________
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Naming of Ionic Compounds
Cations 1st -Anions 2nd
Co(OH)2
Sn(OH)4
Sb2S3
Hg(CN)2
SrCO3
Cu(ClO3)2
(NH4)2SO3
Co(BrO)2
cobaltous hydroxide or cobalt (II) hydroxide
stannic hydroxide or tin (IV) hydroxide
antimonous sulfide or antimony (III) sulfide
mercuric cyanide or mercury (II) cyanide
strontium carbonate
cupric chlorate or copper (II) chlorate
ammonium sulfite
cobaltous hypobromite or cobalt (II) hypobromite
Solubility
• Each substance has a characteristic solubility in a liquid
• Generally we are most concerned with the solubility in
water, H2O
• The solubility of salts in water can be categorized into
two groups
Soluble and Insoluble
examples: NaCl is soluble
AgCl is insoluble
Solubility Rules
• All salts of Group I cations and
ammonium ion are soluble
• All salts of the Halides are soluble (except
Ag+, Hg22+, Pb2+)
• All salts of ClO3 -, ClO3 -, NO3 -, OAc-, and
SO42- are soluble (except Ag+, Ba2+ , Ca2+,
Pb2+, and Hg22+ for SO42- )
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Solubility Rules
• All salts of S2- are insoluble (except
Group I and II cations and NH4+ )
• All salts of O2- are insoluble (except
Group I and Ba2+)
• All salts of OH- are insoluble (except
Group I cations, NH4 +, Ba2+, Sr2+, and
Ca2+)
• Most salts of CO32-, PO43-, AsO43-, are
insoluble (except Group I cations and
NH4+)
Neutralization Reactions
(Acid/Base Reactions)
Molecular equation
HCl (aq) + NaOH (aq) --> H2O(l) + NaCl(aq)
total ionic equation
H+ (aq) + Cl- (aq) + Na+ (aq) + OH- (aq) --> H2O(l) + Na+ (aq) + Cl-(aq)
Net ionic equation
H+
(aq)
+ OH- (aq) --> H2O(l)
Molecular equation
H2SO4 (aq) + Ba(OH)2 (aq) --> 2H2O(l) + BaSO4(s)
total ionic equation
2H+ (aq) + SO42- (aq) + Ba2+ (aq) + 2OH-(aq) --> 2H2O(l) + BaSO4(s)
Precipitation Reaction
(Metathesis)
Molecular equation
NaCl (aq) + AgNO3 (aq) -->
AgCl(s) + NaCl(aq)
total ionic equation
Na+ (aq) + Cl- (aq) + Ag+ + NO3- (aq) --> AgCl (s) + Na+ + Cl-(aq)
Net ionic equation
Cl- (aq) + Ag+ --> AgCl (s)
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Oxidation/Reduction Reactions
Redox
Molecular equation
CuSO4 (aq) + Zn (s) --> ZnSO4 (aq) + Cu (s)
Net Ionic Equation
Cu2+(aq) + Zn (s) --> Zn2+ (aq) + Cu (s)
Combination Reactions
S (s) + O2 (g) --> SO2 (g)
H2O (l) + CO2(aq) --> H2CO3 (aq)
CaO (s) + H2O (l) --> Ca(OH)2 (s)
Decomposition Reactions
CaCO3 (s) -∆-> CO2 (g) + CaO (s)
HgO (s) -∆-> Hg (l) + 1/2 O2 (g)
Reaction Types
2 classification Schemes
Based on products and
reactants
Based on mode of
reaction
•synthesis/combination rxn
•gas evolution rxn
•decomposition rxn
•precipitation rxn
•double displacement/metathesis
•neutralization rxn
•combustion rxn
•redox rxn
•corrosion rxn
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Combustion Reactions
(not balanced!)
CH4 (g) + O2 (g) --> CO2 (g) + H2O (g)
C6H12O6 (s) + O2 (g) --> CO2 (g) + H2O (g)
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