1 net ionic equations. 2 redox reactions exchangeacid-basereactionsexchangegas-formingreactions...
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REDOX REDOX REACTIONSREACTIONS
REDOX REDOX REACTIONSREACTIONS
EXCHANGEEXCHANGEAcid-BaseAcid-BaseReactionsReactions
EXCHANGEEXCHANGEGas-FormingGas-FormingReactionsReactions
EXCHANGEEXCHANGE:: Precipitation Reactions Precipitation Reactions
REACTIONSREACTIONS
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TerminologyTerminologyTerminologyTerminology
In solution we need to define the In solution we need to define the --
• SOLVENTSOLVENT
the component whose the component whose physical state is physical state is preserved when preserved when solution formssolution forms
• SOLUTESOLUTE
the other solution componentthe other solution component
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IONIC COMPOUNDSIONIC COMPOUNDSCompounds in Aqueous SolutionCompounds in Aqueous Solution
Many reactions involve ionic compounds, Many reactions involve ionic compounds,
especially reactions in water — especially reactions in water — aqueous aqueous solutions.solutions.
KMnOKMnO44 in water in water KK++(aq) + MnO(aq) + MnO44--(aq)(aq)
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How do we know ions are How do we know ions are present in aqueous present in aqueous solutions?solutions?
The solutions The solutions conduct conduct electricity!electricity!
They are called They are called ELECTROLYTESELECTROLYTES
HCl, MgClHCl, MgCl22, and NaCl are , and NaCl are strong strong electrolyteselectrolytes. . They They dissociate completely (or dissociate completely (or nearly so) into ions.nearly so) into ions.
Aqueous Aqueous SolutionsSolutions
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HCl, MgClHCl, MgCl22, and NaCl are , and NaCl are strong strong electrolyteselectrolytes. . They dissociate They dissociate completely (or nearly so) into ions.completely (or nearly so) into ions.
Aqueous Aqueous SolutionsSolutions
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An acid -------> HAn acid -------> H++ in water in waterAn acid -------> HAn acid -------> H++ in water in water
ACIDSACIDSACIDSACIDS
Some Some strongstrong acids areacids are
HClHCl hydrochlorichydrochloric
HH22SOSO44 sulfuricsulfuric
HClOHClO44 perchloricperchloric
HNOHNO33 nitricnitricHNOHNO33
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Strong acids• make up six of all the acids • have weak conjugate bases
Strong Acids
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Strong Bases
Strong bases • are formed from metals of
Groups 1A (1) and 2A (2) • include LiOH, NaOH, KOH,
and Ba(OH)2
• dissociate 100% in water
KOH(s) K+(aq) + OH−(aq)
Bases in household products are used to remove grease and to open drains.
11Aqueous Aqueous SolutionsSolutions
Acetic acid ionizes only to a small extent, so Acetic acid ionizes only to a small extent, so it is a it is a weak electrolyte.weak electrolyte.CHCH33COCO22H(aq)H(aq) ---> ---> CHCH33COCO22
--(aq) + H(aq) + H++(aq)(aq)
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Weak AcidsWeak AcidsWeak AcidsWeak AcidsWEAK ACIDS = weak WEAK ACIDS = weak
electrolyteselectrolytes
CHCH33COCO22HH
acetic acidacetic acid
HH22COCO33 carbonic acidcarbonic acid
HH33POPO44 phosphoric phosphoric acidacid
HFHF
hydrofluoric acidhydrofluoric acid
Acetic acid
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Weak acids• make up most of the acids• have strong conjugate bases
Weak Acids
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Weak Bases
Weak bases • are poor acceptors of protons• dissociate only slightly in water• produce only a few ions in water• are used in household products
such as cleaners
NH3(g) + H2O(l) NH4+(aq) + OH−(aq)
15AqueouAqueou
s s SolutionSolution
ssAcetic acid ionizes only to a small Acetic acid ionizes only to a small extent, so it is a extent, so it is a weak weak electrolyte.electrolyte.
CHCH33COCO22H(aq)H(aq) ---> ---> CHCH33COCO22--(aq) + (aq) +
HH++(aq)(aq)
16Aqueous Aqueous SolutionsSolutions
Some compounds Some compounds dissolve in water but do dissolve in water but do not conduct electricity. not conduct electricity. They are called They are called nonelectrolytes.nonelectrolytes.
Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol
Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol
Basic Chemistry Copyright © 2011 Pearson Education, Inc.17
Learning Check
Identify each of the following as a strong or weak acid or base:
A. HBr
B. HNO2
C. NaOH
D. H2SO4
E. Cu(OH)2
strong acid
weak acid
strong basestrong acid
weak base
Basic Chemistry Copyright © 2011 Pearson Education, Inc.18
Learning Check
A. Identify the stronger acid in each pair.
1. HNO2 or H2S
2. HCO3- or HBr
3. H3PO4 or H3O+
B. Identify the stronger base in each pair.
1. NO3- or F-
2. CO32- or NO2
-
3. OH- or H2O
Basic Chemistry Copyright © 2011 Pearson Education, Inc.
Acid-Base ReactionsAcid-Base Reactions The “driving force” = formation of water.The “driving force” = formation of water.
NaOH (NaOH (aqaq) + HCl () + HCl (aqaq) ) ’’
NaCl (NaCl (aqaq) + H) + H22O (l)O (l)
Net ionic equationNet ionic equation
OHOH- - ((aqaq) + H) + H+ + ((aqaq) ) ’’ H H22O (l)O (l)
This applies to ALL reactions This applies to ALL reactions
of of STRONGSTRONG acids and bases. acids and bases.
Basic Chemistry Copyright © 2011 Pearson Education, Inc.
Gas-Forming Gas-Forming ReactionsReactions
The chemistry of The chemistry of metal carbonatesmetal carbonates..
COCO22 and water and water ’’ H H22COCO33
HH22COCO3 3 ((aqaq) + Ca) + Ca2+2+ ’’
2 H2 H++((aqaq) + CaCO) + CaCO3 3 (s) (limestone)(s) (limestone)
Adding acid reverses this reaction.Adding acid reverses this reaction.
MCOMCO33 + acid + acid ’’ CO CO22 + salt + salt
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Water Solubility of Ionic Water Solubility of Ionic CompoundsCompounds
Common minerals are often formed with Common minerals are often formed with anions that lead to insolubility:anions that lead to insolubility:
sulfidesulfide fluoridefluoride
carbonatecarbonate oxideoxide
Azurite, a copper carbonate
Iron pyrite, a sulfideOrpiment, arsenic sulfide
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Precipitation Precipitation ReactionsReactions
Precipitation Precipitation ReactionsReactions
The “driving force” is the formation of an The “driving force” is the formation of an insoluble compound — a insoluble compound — a precipitateprecipitate..
Pb(NOPb(NO33))2 2 ((aqaq) + 2 KI () + 2 KI (aqaq) ) ’’
2 KNO2 KNO3 3 ((aqaq) + PbI) + PbI2 2 ((ss))
Net ionic equationNet ionic equation
PbPb2+ 2+ ((aqaq) + 2 I) + 2 I- - ((aqaq) ) ’’ PbI PbI2 2 ((ss))
28Net Ionic Net Ionic EquationsEquationsNet Ionic Net Ionic EquationsEquations
Mg(s) + 2 HCl(Mg(s) + 2 HCl(aqaq) --> H) --> H22(g) + MgCl(g) + MgCl22((aqaq))
We really should writeWe really should write
Mg(s) + 2 HMg(s) + 2 H++((aqaq) + 2 Cl) + 2 Cl--((aqaq) --->) --->
HH22(g) + Mg(g) + Mg2+2+((aqaq) + 2 Cl) + 2 Cl--((aqaq))
The two ClThe two Cl-- ions are ions are SPECTATOR IONSSPECTATOR IONS — — they do not participate.they do not participate.
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Li+(aq) + Na+(aq) + OH-(aq) + CrO4-(aq) ---> Li+(aq) + Na+(aq) + OH-(aq) + CrO4
-(aq) Li+(aq) + Na+(aq) + OH-(aq) + CrO4-(aq) ---> Li+(aq) + Na+(aq) + OH-(aq) + CrO4
-(aq)
Cr3+(aq) + Na+(aq) + NO3-(aq) + Br-(aq) ---> Cr3+(aq) + Na+(aq) + NO3
-(aq) + Br-(aq) Cr3+(aq) + Na+(aq) + NO3-(aq) + Br-(aq) ---> Cr3+(aq) + Na+(aq) + NO3
-(aq) + Br-(aq)
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If one ion from the If one ion from the “Soluble Compd.” list is “Soluble Compd.” list is present in a compound, present in a compound, the compound is water the compound is water
soluble.soluble.
Water Solubility of Ionic Water Solubility of Ionic CompoundsCompounds
Screen 5.4 & Figure 5.1
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