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Chapter 5 Molecular View of
Reactions in Aqueous Solutions
Chemistry: The Molecular Nature of Matter, 6E
Jespersen/Brady/Hyslop
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions in Solution
For reaction to occur Reactants needs to come into physical
contact
Happens best in gas or liquid phase Movement occurs
Solution Homogeneous mixture
2 or more components mix freely
Molecules or ions completely intermingled
Contains at least 2 substances
2
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Definitions:Solvent Medium that dissolves solutes
Component present in largest amount Can be gas, liquid, or solid Liquids most common Aqueous solution—water is solvent
Solute Substance dissolved in solvent
Solution is named by solute Can be gas—CO2 in soda Liquid—Ethylene glycol in antifreeze Solid—Sugar in syrup
3
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Iodine Molecules in Ethanol
4
Crystal of solute placed in solvent
Solute molecules dispersed throughout solvent
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Solutions May be characterized using
Concentration Solute-to-solvent ratio
Percent Concentration
5
solvent solute
gg
solution solute
gg
solution 100solute
ionconcentrat %g
g
or
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Relative ConcentrationDilute solution
Small solute to solvent ratio
Ex. Eyedrops
Concentrated solution Large solute to solvent
ratio
Ex. Pickle brine
Dilute solution contains less solute per unit volume than more concentrated solution
6
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
ConcentrationSolubility
Temperature dependent
Saturated solution Solution in which no more solute can be
dissolved at a given temperature
Unsaturated solution Solution containing less solute than
maximum amount Able to dissolve more solute
7
solvent g 100solution saturated make to needed g
Solubilitysolute
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Solubilities of Some Common Substances
8
Substance Formula
Solubility (g/100 g water)
Sodium chloride
NaCl 35.7 at 0°C39.1 at 100°C
Sodium hydroxide
NaOH 42 at 0°C347 at 100°C
Calcium carbonate
CaCO3 0.0015 at 25°C
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
ConcentrationsSupersaturated Solutions
Contains more solute than required for saturation at a given temperature
Formed by careful cooling of saturated solutions
Unstable Crystallize out when add seed crystal –
results in formation of solid or precipitate (ppt.)
9
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
PreciptatesPrecipitate
Solid product formed when reaction carried out in solutions and one product has low solubility
Insoluble product
Separates out of solution
Precipitation reaction Reaction that produces precipitate
Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq)
1 mol Pb(NO3)2 2 mol KI
0.100 mol Pb(NO3)2 0.200 mol KI
10
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Electrolytes in Aqueous Solution Ionic compounds conduct electricity
Molecular compounds don’t conduct electricityWhy?
11
Bright light
No light
Molecular
Ions present
CuSO4 & water Sugar & water
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Ionic Compounds (Salts) in Water H2O molecules arrange themselves
around ions & remove them from lattice.Dissociation
Break salts apart into ions when enter solution
Separated ions Hydrated Conduct electricity
Note: Polyatomic ions remain intact Ex. KIO3 K+ + IO3
12
NaCl(s) Na+(aq) + Cl–(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Molecular Compounds In Water When molecules dissolve in water
Solute particles are surrounded by water Molecules are not dissociated
13
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Electrical ConductivityElectrolyte
Solutes that yield electrically conducting solutions
Separate into ions when enter into solution
Strong electrolyte Electrolyte that dissociates 100% in water
Yields aqueous solution that conducts electricity
Good electrical conduction
Ionic compounds
Strong acids and bases
Ex. NaBr, KNO3, HClO4, HCl14
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Electrical Conductivity
Weak electrolyte Aqueous solution that weakly conducts
electricity due to low ionization
Weak acids and bases
Ex. Acetic acid (HC2H3O2), ammonia (NH3)
Non-electrolyte Aqueous solution that doesn’t conduct
electricity
Molecules remain intact in solution
Ex. Sugar, alcohol
15
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
How many ions form on the dissociation of Na3PO4?
A. 1
B. 2
C. 3
D. 4
E. 8
16
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
How many ions form on the dissociation of Al2(SO4)3?
A.2
B.3
C.5
D.9
E.14
17
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equations for Dissociation Reactions
Ionic compound dissolves to form hydrated ions Hydrated = surrounded by water molecules
In chemical equations, hydrated ions are indicated by Symbol (aq) after each ions
Ions are written separately
KBr(s) K+(aq) + Br(aq)
Mg(HCO3)2(s) Mg2+(aq) + 2HCO3(aq)
18
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning CheckWrite the equations that illustrate the dissociation of the following salts:
Na3PO4(aq) →
Al2(SO4)3(aq) →
CaCl2(aq) →
Ca(MnO4)2(aq) →
19
2 Al3+(aq) + 3 SO42(aq)
3 Na+(aq) + PO43(aq)
Ca2+(aq) + 2 Cl(aq)
Ca2+(aq) + 2 MnO4(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equations of Ionic Reactions Consider the reaction of Pb(NO3)2 with KI
20
PbI2(s)Pb2+ NO3– K+ I–
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equations of Ionic Reactions When two soluble ionic solutions are
mixed, sometimes an insoluble solid forms. Three types of equations used to describe
1. Molecular Equation Substances listed as complete formulas
2. Ionic Equation All soluble substances broken into ions
3. Net Ionic Equation Only lists ions that actually take part in
reaction
21
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equations of Ionic Reactions
1. Molecular Equation Complete formulas for all reactants and
products
Formulas written with ions together
Does not indicate presence of ions
Gives identities of all compounds
Good for planning experiments
Ex.
Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq)
22
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equations of Ionic Reactions2. Ionic Equation
Emphasizes the reaction between ions
All strong electrolytes dissociate into ions
Used to visualize what is actually occurring in solution
Insoluble solids written together as they don’t dissociate to any appreciable extent
Ex.
Pb2+(aq) + 2NO3(aq) + 2K+(aq) + 2I(aq)
PbI2(s) + 2K+(aq) + 2NO3
(aq)23
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equations of Ionic ReactionsSpectator Ions
Ions that don’t take part in reaction
They hang around and watch
K+ & NO3 in our example
3. Net Ionic Equation Eliminate all spectator ions
Emphasizes the actual reaction
Focus on chemical change that occurs
Ex. Pb2+(aq) + 2I(aq) PbI2(s)
24
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Net Ionic Equations Many ways to make PbI2
1.Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq)
2.Pb(C2H3O2)2(aq) + 2NH4I(aq) PbI2(s) +
2NH4C2H3O2(aq)
Different starting reagents
Same net ionic equation
Pb2+(aq) + 2I(aq) PbI2(s)
25
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Converting Molecular Equations to Ionic Equations
Strong electrolytes exist as dissociated ions in solution
Strategy
1. Identify strong electrolytes
2. Use subscript coefficients to determine total number of each type of ion
3. Separate ions in all strong electrolytes
4. Show states as recorded in molecular equations
26
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check: Convert Molecular to Ionic Equations:
Write the correct ionic equation for each:
Pb(NO3)2(aq) + 2NH4IO3(aq) → Pb(IO3)2(s) + 2NH4NO3(aq)
2NaCl (aq) + Hg2(NO3)2 (aq) → 2NaNO3 (aq) + Hg2Cl2
(s)
27
2Na+(aq) + 2Cl–(aq) + Hg22+(aq) + 2NO3
–(aq) → 2Na+(aq)
+ 2NO3–(aq) +
Hg2Cl2(s)
Pb2+(aq) + 2NO3–(aq) + 2NH4
+(aq) + 2IO3–(aq) →
Pb(IO3)2(s) + 2NH4+(aq) +
2NO3–(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your TurnConsider the following reaction :
Na2SO4(aq) + BaCl2(aq) → 2NaCl(aq) + BaSO4(s)
Which is the correct ionic equation?
A. 2Na+(aq) + SO42–(aq) + Ba2+(aq) + Cl22–(aq) → 2Na+(aq)
+ 2Cl–(aq) + BaSO4(s)
B. 2Na+(aq) + SO42–(aq) + Ba2+(aq) + 2Cl–(aq) → 2Na+(aq)
+ 2Cl–(aq) + BaSO4(s)
C. 2Na+(aq) + SO42–(aq) + Ba2+(aq) + Cl22–(aq) → 2Na+(aq)
+ 2Cl–(aq) + Ba2+(s) + SO42–(s)
D. Ba2+(aq) + SO42–(aq) → BaSO4(s)
E. Ba2+(aq) + SO42–(aq) → Ba2+(s) + SO4
2–(s)
28
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Converting Ionic Equations to Net Ionic Equations
Strategy1. Identify spectator ions
2. Eliminate from both sides
3. Rewrite equation using only ions that actually react.
4. Show states as recorded in molecular and ionic equations
29
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check: Convert Ionic Equation to Net Ionic Equation
Write the correct net ionic equation for each.
Pb2+(aq) + 2NO3–(aq) + 2K+(aq) + 2IO3
–(aq) →Pb(IO3)2(s) + 2K+
(aq) + 2NO3–(aq)
2Na+(aq) + 2Cl–(aq) + Hg22+(aq) + 2NO3
–(aq) → 2Na+
(aq) + 2NO3–(aq) +
Hg2Cl2(s) 30
2Cl–(aq) + Hg22+(aq) → Hg2Cl2(s)
Pb2+(aq) + 2IO3–(aq) →
Pb(IO3)2(s)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your TurnConsider the following molecular equation:
(NH4)2SO4(aq) + Ba(CH3CO2)2(aq) → 2NH4CH3CO2(aq) +
BaSO4(s)
Which is the correct net ionic equation?
A. Ba2+(aq) + SO42–(aq) → BaSO4(s)
B. 2NH4+(aq) + 2CH3CO2
–(aq) → 2NH4CH3CO2(s)
C. Ba2+(aq) + SO42–(aq) → BaSO4(aq)
D. 2NH4+(aq) + Ba2+(aq) + SO4
2–(aq) + 2CH3CO2–(aq) →
2NH4+(aq) + 2CH3CO2
–(aq) + BaSO4(s)
E. 2NH4+(aq) + 2CH3CO2
–(aq) → 2NH4CH3CO2(aq)31
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Criteria for Balancing Ionic and Net Ionic Equations
Material Balance There must be the same number of
atoms of each kind on both sides of the arrow
Electrical Balance The net electrical charge on the left must
equal the net electrical charge on the right
Charge does not have to be zero
32
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check: Balancing Equations for Mass & Charge
Balance Molecular Eqn. for mass 2Na3PO4(aq) + 3Pb(NO3)2(aq) 6NaNO3(aq) +
Pb3(PO4)2(s)
Can keep polyatomic ions together when counting
Balance Ionic Eqn. for charge
6Na+(aq) + 2PO43(aq) + 3Pb2+(aq) + 6NO3
(aq)
6Na+(aq) + 6NO3(aq) + Pb3(PO4)2(s)
Charge must add up to zero on both sides.
Net Ionic Eqn. Balanced for both mass & charge 3Pb2+(aq) + 2PO4
3(aq) Pb3(PO4)2(s)
33
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acids & Bases as Electrolytes Many common laboratory chemicals and
household products
Indicators Dye molecules that change color
in presence of acids or bases
Acids Turn blue litmus red Lemon juice, vinegar, H2SO4
Bases Turn red litmus blue Drano (lye, NaOH), ammonia (NH3)
34
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Neutralization Reaction Important reaction of acids and bases Acid reacts with base to form water and salt
(ionic compound).
Acid + base salt + H2O
Ex. HCl(aq) + NaOH(aq) NaCl(aq) + H2O
HBr(aq) + LiOH(aq) LiBr(aq) + H2O
1:1 mole ratio of acid:base gives neutral solution
Ionization reactions Ions form where none have been before
Reactions of acids or bases with water35
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Arrhenius Acid-base neutralization is
H+(aq) + OH–(aq) H2O
In solution, H+ attaches itself to H2O to form H3O+ or hydronium ion in water
H+ does not ever exist in aqueous solution
When H3O+ reacts, it releases H+
H+ is active ingredient
Often use just H+ for simplicity
36
)()(OH
)( Cl HHCl 2 aqaqg
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Arrhenius Acid Substance that reacts with water to
produce the hydronium ion, H3O+
Acid + H2O Anion + H3O+
HA + H2O A– + H3O+
HC2H3O2(aq) + H2O H3O+(aq) + C2H3O2−(aq)
37
HCl(g) + H2O Cl–(aq) + H3O+(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acids Categorized by Number of H+sMonoprotic Acids
Furnish only one H+
HNO3(aq) + H2O H3O+(aq) + NO3–(aq)
HC2H3O2(aq) + H2O H3O+(aq) + C2H3O2–
(aq)
Polyprotic acids Furnish more than one H+
Diprotic acids — furnish two H+
H2SO3(aq) + H2O H3O+(aq) + HSO3–(aq)
HSO3–(aq) + H2O H3O+(aq) + SO3
2–(aq) 38
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acids Catagorized by Number of H+sPolyprotic acids
Triprotic acids — furnish three H+
H3PO4 H2PO4– HPO4
2– PO43–
Stepwise equations
H3PO4(aq) + H2O H3O+(aq) + H2PO4–(aq)
H2PO4–(aq) + H2O H3O+(aq) + HPO4
2–(aq)
HPO42–(aq) + H2O H3O+(aq) + PO4
3–(aq)
Net:
H3PO4(aq) + 3H2O 3H3O+(aq) + PO43–(aq)
39
–H+ –H+ –H+
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acidic Anhydrides Nonmetal Oxides
Act as Acids
React with water to form molecular acids that contain hydrogen
SO3(g) + H2O H2SO4(aq)
sulfuric acid
N2O5(g) + H2O 2HNO3(aq)
nitric acid
CO2(g) + H2O H2CO3(aq)
carbonic acid40
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Arrhenius Bases Ionic compounds that contain hydroxide
ion, OH–, or oxide ion, O2–.or
Molecular compounds that react with water to give OH–.
1. Ionic compounds containing OH– or O2–
a. Metal Hydroxides Dissociate into metal & hydroxide ions
NaOH(s) Na+(aq) + OH–(aq)
Mg(OH)2(s) Mg2+(aq) + 2OH–
(aq) 41
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Ionic Oxidesb. Basic Anhydrides
Soluble metal oxides Undergo ionization (hydrolysis) reaction to
form hydroxide ions Oxide reacts with water to form metal
hydroxide
CaO(s) + H2O Ca(OH)2(aq)
Then metal hydroxide dissociates in water
Ca(OH)2(aq) Ca2+(aq) + 2OH–(aq) 42
2OH–O2– H2O
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Strong vs. Weak Electrolyte
43
HCl(aq) CH3COOH(aq) NH3(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Strong Acids
Dissociate completely when dissolved in waterEx. HBr(g) + H2O H3O+(aq) + Br–(aq)
Good electrical conduction Any acid not on this list, assume weak
HClO4(aq) perchloric acid
HClO3(aq) chloric acid
HCl(aq) hydrochloric acidHBr(aq) hydrobromic acidHI(aq) hydroiodic acid
HNO3(aq) nitric acid
H2SO4(aq) sulfuric acid
44
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Arrhenius Bases2. Molecular Bases
Undergo ionization (hydrolysis) reaction to form hydroxide ions
Base + H2O BaseH+(aq) + OH–(aq)
B + H2O BH+(aq) + OH–(aq)
NH3(aq) + H2O NH4+(aq) + OH–(aq)
45
NH3 H2O NH4+ OH–
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Strong Bases Bases that dissociate completely in water
Soluble metal hydroxides KOH(aq) K+(aq) + OH–(aq)
Good electrical conductors Behave as (aq) ionic compounds Common strong bases are:
Group IA metal hydroxides LiOH, NaOH, KOH, RbOH, CsOH
Group IIA metal hydroxides
Ca(OH)2, Sr(OH)2, Ba(OH)2
46
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Weak Acids Any acid other than 7 strong acids Only ionize partially (<100%)
Organic acids HC2H3O2(aq) + H2O H3O+(aq) + C2H3O2
–(aq)
Ex. HCO2H(aq) + H2O H3O+(aq) + HCO2
–(aq)47
Only this H comes off as H+
Acetic AcidMolecule,HC2H3O2
Acetate ion, C2H3O2
–
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Why is Acetic Acid Weak?
48
H3O+(aq) + C2H3O2–(aq) HC2H3O2(aq) +
H2O
H2O + C2H3O2–(aq) HC2H3O2(aq) + H3O+
(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Dynamic Equilibrium 2 opposing reactions occurring at same rate Also called Chemical equilibrium
Equilibrium Concentrations of substances present in
solution do not change with time
Dynamic Both opposing reactions occur continuously
Represented by double arrowHC2H3O2(aq) + H2O H3O+(aq) + C2H3O2
–
(aq)
Forward reaction – Forms ions
Reverse reaction – Removes ions49
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Weak Bases Molecular bases Do not dissociate Accept H+ from water inefficiently Accept H+ from acids preferentially
NH3(aq) + HCl(aq) NH4Cl(aq)
Ex.
NH3(aq) + H2O NH4+(aq) + OH(aq)
Or for general base
B(aq) + H2O BH+(aq) + OH(aq)
50
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Equilibrium for Weak BaseForward reaction
51
Reverse reaction
Net is dynamic equilibriumNH3(aq) + H2O NH4
+(aq) + OH(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Position of Equilibrium Extent of completion Depends on electrolyte
Strong electrolyte Large % ionizes dominant Mostly products
Strong acids & bases Little back reaction Write eqn. as
52
Weak electrolyte Small % ionizes dominant Mostly reactants
Weak acids and bases
Lots of back reaction Write eqn. as
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check Write the ionization equation for each of
the following with water:
1.Weak base methylamine, CH3NH2.
2.Weak acid nitrous acid, HNO2.
3.Strong acid chloric acid, HClO3.
4.Strong base strontium hydroxide, Sr(OH)2.
53
CH3NH2(aq) + H2O CH3NH3+(aq) + OH–(aq)
HClO3(aq) + H2O H3O+(aq) + ClO3–(aq)
Sr(OH)2(aq) Sr2+(aq) + 2 OH–
(aq)
HNO2(aq) + H2O H3O+(aq) + NO2–
(aq)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
Which of the following is a weak acid?
A.HCl
B.HNO3
C.HClO4
D.HC2H3O2
E.H2SO4
54
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
Which of the following is not a strong base?
A.NaOH
B.CH3NH2
C.Cs2O
D.Ba(OH)2
E.CaO
55
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
Which of the following is not a product of the reaction:
NH3(aq) +HCN(aq) ?
A.CN–(aq)
B.NH4+(aq)
C.NH3CN(s)
D.H2O
E.HCN
56
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acid—Base Nomenclature System for naming acids and bases
Acids Hydrogen compounds of non-metals =
binary acids
Hydrogen compounds of oxoanions = Oxoacids
Naming acid salts
Bases Metal Hydroxides and oxides = ionic
Molecular = molecular names57
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming AcidsA. Binary Acids — hydrogen + nonmetal
Take molecular name Drop –gen from H name Merge hydro– with nonmetal name Replace –ide with –ic acid
Name of Molecular compound
Name of Aqueous Binary Acid
HCl(g)
hydrogen chloride
HCl(aq)
hydrochloric acid
H2S(g)
hydrogen sulfide
H2S(aq)
hydrosulfuric acid
58
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming AcidsB. Oxo Acids
Acids with hydrogen, oxygen and another nonmetal element
Most of the polyatomic ions in Table 3.5
To name: Based on parent oxoanion name
Take parent ion name
Anion ends in –ate change to –ic (more O's)
Anion ends in –ite change to–ous (less O's)
End name with acid to indicate H+
59
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Oxoacids (Aqueous)Named according to the anion suffix
Anion ends in -ite, acid name is -ous acid
Anion ends in -ate, acid name is -ic acid
Name of Parent Oxoanion
Name of Oxoacid
NO3 HNO3
SO42 H2SO4
ClO2 HClO2
PO32 H2PO3
60
sulfate
chlorite
phosphite
sulfuric acid
chlorous acid
phosphorous acid
nitrate nitric acid
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check: Name Each Aqueous Acid
HNO2
HCN
HClO4
HF
H2CO3
nitrous acid hydrocyanic acid perchloric acid hydrofluoric acid carbonic acid
61
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
Which of the following is the correct name for HClO4 (aq)?
A. chloric acid
B. hydrochloric acid
C. perchloric acid
D. hypochlorous acid
E. chlorous acid
62
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn
Which of the following is the correct name for H2SO3(aq)?
A.sulfuric acid
B.sulfurous acid
C.hydrosulfuric acid
D.hydrosulfurous acid
E.hydrogen sulfite acid
63
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acid Salts If polyprotic acids are neutralized stepwise
Can halt neutralization before all H+’s are removed
Must specify # of H's that remain on salt
Acid salt Ion containing H+ and anion
Contains anion capable of furnishing additional hydrogen ions
H2SO4(aq) + KOH(aq) KHSO4(aq) + H2O(ℓ)
acid salt
64
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Acid Salts—Polyprotic Must specify number of hydrogens still
attached to the anion Can be neutralized by additional base
Ex. Na2HPO4
NaH2PO4
KHSO4
Some acid salts have common names
NaHCO3
65
sodium hydrogen carbonate or sodium bicarbonate
sodium hydrogen phosphate
sodium dihydrogen phosphate
potassium hydrogen sulfate
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
C. Naming BasesOxides & Hydroxides
Ionic compounds Named like ionic compounds
Ca(OH)2 calcium hydroxide
Li2O lithium oxide
Molecular Bases Named like molecules
NH3 ammonia
CH3NH2 methylamine
(CH3)2NH dimethylamine
(CH3)3N trimethylamine66