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Net ionic equationsNet ionic equations

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EXCHANGEEXCHANGEAcid-BaseAcid-BaseReactionsReactions

EXCHANGEEXCHANGEGas-FormingGas-FormingReactionsReactions

EXCHANGEEXCHANGE:: Precipitation Reactions Precipitation Reactions

REACTIONSREACTIONS

Redox ReactionsRedox Reactions

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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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An Ionic An Ionic Compound, Compound,

CuClCuCl22, in , in WaterWater

CCR, page 149CCR, page 149

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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

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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

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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.

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Basic Chemistry Copyright © 2011 Pearson Education, Inc.

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

Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Basic Chemistry Copyright © 2011 Pearson Education, Inc.

EXCHANGEEXCHANGEAcid-BaseAcid-BaseReactionsReactions

EXCHANGEEXCHANGEGas-FormingGas-FormingReactionsReactions

REACTIONSREACTIONS