Introduction to Introduction to Acids, Bases and SaltsAcids, Bases and Salts

Arrhenius Definition of Arrhenius Definition of Acids and BasesAcids and Bases

Acids produce HAcids produce H++ in aqueous (water) solutions in aqueous (water) solutions waterwater

HCl HCl H H+ + (aq) + Cl(aq) + Cl- - (aq)(aq)

Bases produce OHBases produce OH-- in aqueous (water) solutions in aqueous (water) solutions

waterwater

NaOHNaOH Na Na+ + (aq) + OH(aq) + OH- - (aq)(aq)

The Hydronium Ion (HThe Hydronium Ion (H3300++))

Acids produce the HAcids produce the H++ ion ion

This is just a “bare proton” This is just a “bare proton” and is very reactive.and is very reactive.

It immediately forms a It immediately forms a coordinate covalent bond coordinate covalent bond with nearby water with nearby water molecules to form (Hmolecules to form (H3300++).).

AcidsAcids

Produce HProduce H++ (as H (as H33OO++) ions in water) ions in water

Electrolytes (conduct in solution)Electrolytes (conduct in solution)

Taste sour Taste sour

pH is < 7 pH is < 7

Corrode metals (see Table J)Corrode metals (see Table J)

React with bases to form salts and waterReact with bases to form salts and water

(Neutralization)(Neutralization)

BasesBases

Produce OHProduce OH-- ions in water ions in water

Electrolytes (conduct in solution)Electrolytes (conduct in solution)

Taste bitter, chalkyTaste bitter, chalky

pH is >7pH is >7

Feel soapy, slipperyFeel soapy, slippery

React with acids to form salts and waterReact with acids to form salts and water

(Neutralization)(Neutralization)

7

Learning CheckLearning Check

Describe the solution in each of the following Describe the solution in each of the following as: as: 1) acid 2) base or 3)neutral.1) acid 2) base or 3)neutral.

A. ___sodaA. ___soda

B. ___soapB. ___soap

C. ___coffeeC. ___coffee

D. ___ wineD. ___ wine

E. ___ waterE. ___ water

F. ___ grapefruitF. ___ grapefruit

8

SolutionSolution

Describe each solution as: Describe each solution as:

1) acid 2) base or 3) neutral.1) acid 2) base or 3) neutral.

A. A. _1__1_ soda soda

B. B. _2__2_ soap soap

C. C. _2__2_ coffee coffee

D. D. _1__1_ wine wine

E. E. _3__3_ water water

F. F. _1__1_ grapefruit grapefruit

9

Learning CheckLearning Check

Identify each as characteristic of an Identify each as characteristic of an

A) acid or B) baseA) acid or B) base

____ 1. Sour taste ____ 1. Sour taste

____ 2. Produces OH____ 2. Produces OH-- in aqueous solutions in aqueous solutions

____ 3. Chalky taste____ 3. Chalky taste

____ 4. Is an electrolyte____ 4. Is an electrolyte

____ 5. Produces H____ 5. Produces H++ in aqueous solutions in aqueous solutions

10

SolutionSolution

Identify each as a characteristic of anIdentify each as a characteristic of an

A) acid or B) baseA) acid or B) base

__AA__ 1. Sour taste 1. Sour taste

__BB__ 2. Produces OH 2. Produces OH-- in aqueous solutions in aqueous solutions

__BB__ 3. Chalky taste 3. Chalky taste

A, BA, B 4. Is an electrolyte4. Is an electrolyte

__AA__ 5. Produces H 5. Produces H++ in aqueous solutions in aqueous solutions

11

Some Common AcidsSome Common AcidsSee Table KSee Table K

HClHCl hydrohydrochlorchloric acidic acid

HNOHNO33 nitrnitric acidic acid

HH33POPO44 phosphorphosphoric acidic acid

HH22SOSO44 sulfursulfuric acidic acid

HCHC22HH33OO22 acetacetic acidic acid

Naming Acids (Honors)Naming Acids (Honors)

Binary AcidsBinary Acids (Contain 2 elements only)(Contain 2 elements only)

Ex:Ex: HCl, HBr, HHCl, HBr, H22S, HFS, HF

Hydro __________ ic AcidHydro __________ ic Acid

Naming Acids (Honors)Naming Acids (Honors)

Ternary AcidsTernary Acids (Contain hydrogen and a polyatomic ion)(Contain hydrogen and a polyatomic ion)Do NOT start with “Hydro”Do NOT start with “Hydro”

Look at name of polyatomic ionLook at name of polyatomic ion

If it ends in “ate” the acid ends in “ic”If it ends in “ate” the acid ends in “ic”

If it ends in “ite” the acid ends in “ous”If it ends in “ite” the acid ends in “ous”

Name These AcidsName These Acids

HBrHBrHNOHNO33

HH33POPO44

HNOHNO22

HH22CC22OO44

HClOHClOHBrOHBrOHClOHClO44

HH22SS

HIOHIO33

Name These AcidsName These Acids

HBr = hydrobromic acidHBr = hydrobromic acid

HNOHNO3 3 = nitric acid= nitric acid

HH33POPO4 4 = phosphoric acid= phosphoric acid

HNOHNO22 = nitrous acid = nitrous acid

HH22CC22OO4 4 = oxalic acid= oxalic acid

HClO = hypochlorous acidHClO = hypochlorous acid

HBrO = hypobromous acidHBrO = hypobromous acid

HClOHClO4 4 = perchloric acid= perchloric acid

HH22S = hydrosulfuric acidS = hydrosulfuric acid

HIOHIO3 3 = iodic acid= iodic acid

Organic AcidsOrganic Acids

Contain carbon Contain carbon Only one of the hydrogens is “acidic” and Only one of the hydrogens is “acidic” and

dissociates in solutiondissociates in solutionEx:Ex: Acetic AcidAcetic Acid

HCHC22HH33OO22 or or CHCH33COOHCOOH

Naming BasesNaming Bases

Name them like any other ionic compound.Name them like any other ionic compound.

Name usually ends in “hydroxide”Name usually ends in “hydroxide”

Ex: LiOH = lithium hydroxideEx: LiOH = lithium hydroxide

18

Some Common BasesSome Common BasesSee Table LSee Table L

NaOHNaOH sodium hydroxidesodium hydroxide

KOHKOH potassium hydroxidepotassium hydroxide

Ba(OH)Ba(OH)22 barium hydroxidebarium hydroxide

Mg(OH)Mg(OH)22 magnesium hydroxide magnesium hydroxide

Al(OH)Al(OH)33 aluminum hydroxidealuminum hydroxide

Important NoteImportant Note

There are no “organic bases” (containing There are no “organic bases” (containing carbon).carbon).

CC22HH55OH for example is not a base.OH for example is not a base.

It is an alcohol. The OH on this molecule It is an alcohol. The OH on this molecule does not dissociate to form OHdoes not dissociate to form OH- - (hydroxide (hydroxide ion)ion)

SaltsSalts

““Salts” are ionic compounds that are not Salts” are ionic compounds that are not acids or bases.acids or bases.

Metal cation (+) & nonmetal anion (-)Metal cation (+) & nonmetal anion (-)They are electrolytesThey are electrolytes

Ex: NaCl, MgSOEx: NaCl, MgSO44, Li, Li22SS

21

Learning Check Learning Check

Acid, Base Acid, Base NameNameor Saltor Salt

CaClCaCl2 2 ____________ ______________________________

KOHKOH ____________ ______________________________

Ba(OH)Ba(OH)2 2 ____________ _______________ _______________

HBrHBr ____________ ______________________________

HH22SOSO44 ____________ ________________________________

AnswersAnswers

Acid,Base Nameor Salt

CaCl2 salt calcium chloride

KOH base potassium hydroxide

Ba(OH)2 base barium hydroxide

HBr acid hydrobromic acid

H2SO4 acid sulfuric acid

DissociationDissociation

Dissociation:Dissociation: when a compound splits when a compound splits apart into ions in solution.apart into ions in solution.

How might these dissociate?How might these dissociate?

HH22SOSO44

KOHKOH

Acids React with MetalsAcids React with Metals

See Reference Table JSee Reference Table JMetals above Hydrogen on the table will react Metals above Hydrogen on the table will react

with acids to form a salt and Hwith acids to form a salt and H22 gas gas

Single Replacement ReactionSingle Replacement Reaction

2Zn(s) + 2HCl(aq) ZnCl2Zn(s) + 2HCl(aq) ZnCl22(aq) + H(aq) + H22(g)(g)

Will an acid react with these metals?Will an acid react with these metals?

If so complete and balance the single If so complete and balance the single replacement reaction.replacement reaction.

Mg + HNOMg + HNO33

Cu + HClCu + HCl

Ca + HCa + H22SOSO44

AnswersAnswers

Mg + 2HNOMg + 2HNO33 Mg(NOMg(NO33))22 + H + H22

Cu + HClCu + HCl No reaction Cu in below No reaction Cu in below hydrogen on Table Jhydrogen on Table J

Ca + HCa + H22SOSO44 Ca(SOCa(SO44) + H) + H22

Acid, Bases and Metals BBC (good for Acid, Bases and Metals BBC (good for Indicators)Indicators)

http://www.bbc.co.uk/schools/ks3bitesize/shttp://www.bbc.co.uk/schools/ks3bitesize/science/chemical_material_behaviour/acidscience/chemical_material_behaviour/acids_bases_metals/activity.shtml_bases_metals/activity.shtml

Pure Water is NeutralPure Water is Neutral

Self Ionization of Water:Self Ionization of Water: a small quantity of a small quantity of water molecules in a sample will self ionize.water molecules in a sample will self ionize.

This results in a small, but equal amount of HThis results in a small, but equal amount of H++ and OHand OH--

HH22O O H H++ + OH + OH--

Hydrogen Ion = Hydroxide Ion Hydrogen Ion = Hydroxide Ion

[H[H++] = [OH] = [OH--]]

H+ OH-

Self Ionization of WaterSelf Ionization of Water

http://youtu.be/kW-Zk4zABzwhttp://youtu.be/kW-Zk4zABzw

AcidsAcids

Increase the HIncrease the H++ concentration concentration

As HAs H++ increases, OH increases, OH-- decreases decreases

[H[H++] > ] > [OH[OH--]]H+

OH-

BasesBases

Increase the hydroxide ion (OHIncrease the hydroxide ion (OH--) )

concentrationconcentration

When OHWhen OH-- increases, H increases, H++ decreases decreases

[OH[OH]] > > [H[H++]]

H+OH-

Important SummaryImportant Summary

Acidic:Acidic: [H+] > [OH-][H+] > [OH-]Basic:Basic: [H+] < [OH-][H+] < [OH-]Neutral:Neutral: [H+] = [OH-][H+] = [OH-]

Determining if it is an Acid or Base Determining if it is an Acid or Base

How can you tell if something is acidic or How can you tell if something is acidic or basic?basic?

Use an electronic pH meterUse an electronic pH meter

Use an indicator such as Use an indicator such as litmuslitmus

Use pH paper containing universal indicatorUse pH paper containing universal indicator

Acid/Bases IndicatorsAcid/Bases IndicatorsSee Table MSee Table M

ExamplesExamples:: LitmusLitmus

pH range for color change (4.5 – 8.3)pH range for color change (4.5 – 8.3) Color change: red to blue Color change: red to blue

PhenolphthaleinPhenolphthalein pH range for color change (8 - 9)pH range for color change (8 - 9) Color change: colorless to pinkColor change: colorless to pink

What color would these be if the What color would these be if the pH = 10? pH = 10? pH = 3?pH = 3?

pH ScalepH Scale

0 1 2 3 4 5 6 7 8 90 1 2 3 4 5 6 7 8 9 10 11 12 13 1410 11 12 13 14

NeutralNeutral

[H[H++]]>>[OH[OH--]] [H[H++] = [OH] = [OH--]] [OH[OH--]]>>[H[H++]]

Acidic Basic

Pretty HydrangeasPretty Hydrangeas

The color of hydrangea flowers depends The color of hydrangea flowers depends on the pH of the soil.on the pH of the soil.

What is pH?What is pH?

Tells us the relative quantity of HTells us the relative quantity of H++ ions (or ions (or the acidity) in solution.the acidity) in solution.

The greater the [HThe greater the [H++] the ] the lower the pH.lower the pH.

Calculating pHCalculating pH

pH = - log [HpH = - log [H++]]

From the French From the French pouvoir hydrogene pouvoir hydrogene

(“hydrogen power” or power of (“hydrogen power” or power of

hydrogen)hydrogen)

43

[H[H++]] pHpH

1 x 101 x 10--55 M M 55

1 x 101 x 10--99 M M 99

1 x 101 x 10--1111 MM 1111

Calculating pOHCalculating pOH

What if you are given the concentration of What if you are given the concentration of a base?a base?

Ex: .000001M LiOHEx: .000001M LiOH

You need to find the pOH!!You need to find the pOH!!

pOHpOH

pOH = -log [OHpOH = -log [OH--]]

Ex: Ex: .000001M LiOH = 1 x 10.000001M LiOH = 1 x 10-6-6

pOH = 6pOH = 6

Ex: Ex: .0001M NaOH = 1 x 10.0001M NaOH = 1 x 10-4-4

pOH = 4pOH = 4

How can you find pH of a Base?How can you find pH of a Base?

Easy!!!Easy!!!

pH + pOH = 14pH + pOH = 14

Ex: Ex: .000001M LiOH = 1 x 10.000001M LiOH = 1 x 10-6-6

pOH = 6pOH = 6pH = 8pH = 8

Ex: Ex: .0001M NaOH = 1 x 10.0001M NaOH = 1 x 10-4-4

pOH = 4pOH = 4pH = 10pH = 10

KwKw

If you know the concentration of one ion you If you know the concentration of one ion you can find the other!can find the other!

[H+] x [OH-] = 1 x 10[H+] x [OH-] = 1 x 10-14-14

This is called the Kw This is called the Kw

Or the “ion product” of water.Or the “ion product” of water.

So what is the [OH-] is the [H+] is .001M?So what is the [OH-] is the [H+] is .001M?

[1 x 10[1 x 10-3-3] x [OH-] = 1 x 10] x [OH-] = 1 x 10-14-14

[OH-] = 1 x 10[OH-] = 1 x 10-11-11

Everything keeps adding up to 14!!Everything keeps adding up to 14!!What’s up with that?What’s up with that?

Let’s Try ItLet’s Try It

You have a .001 HCl solution.You have a .001 HCl solution.

Find: [H+], [OH-], pH, pOHFind: [H+], [OH-], pH, pOH

Let’s Try ItLet’s Try It

You have a .000000001M NaOH solution.You have a .000000001M NaOH solution.

Find: [H+], [OH-], pH, pOHFind: [H+], [OH-], pH, pOH

Equation SummaryEquation Summary

pH = -log [HpH = -log [H++ ] ] pOH = -log [OHpOH = -log [OH-- ] ]

[H[H++ ] = 10 ] = 10-pH-pH [OH[OH-- ] = 10 ] = 10-pOH-pOH

pH + pOH = 14pH + pOH = 14 [H[H++ ] x [OH ] x [OH-- ] = 1x10 ] = 1x10-14-14

Acidic solution: Acidic solution: pH < 7pH < 7 pOH > 7pOH > 7

Neutral solution: Neutral solution: pH = 7pH = 7 pOH = 7pOH = 7

Basic solution: Basic solution: pH > 7pH > 7 pOH < 7pOH < 7

pH and pOH gamepH and pOH gamehttp://www.quia.com/rr/4051.htmlhttp://www.quia.com/rr/4051.html

Honors QuestionsHonors Questions

If the pH of a solution is 3.25 find the pOH,If the pH of a solution is 3.25 find the pOH,

[H+], and [OH-].[H+], and [OH-].

If .065 mole of KOH is placed in 20 liters ofIf .065 mole of KOH is placed in 20 liters of

water, what is the resulting pH?water, what is the resulting pH?

Acid RainAcid Rain

(Not to be confused with (Not to be confused with “Chocolate Rain”)“Chocolate Rain”)

Acid RainAcid Rain

Unpolluted rain has Unpolluted rain has

a pH of 5.6 a pH of 5.6

It is naturally acidic It is naturally acidic

due to the gases in due to the gases in

the air that dissolve the air that dissolve

in it.in it.

Acid RainAcid Rain

Rain with a pH Rain with a pH

below 5.6 is “acid below 5.6 is “acid

rain“rain“

pH of RainwaterpH of Rainwateracross United States in 2001across United States in 2001

Sources of Acid RainSources of Acid Rain

Sources of Acid RainSources of Acid Rain

Power stationsPower stations

Oil refineriesOil refineries

Coal with high S contentCoal with high S content

Car and truck emissionsCar and truck emissions

Bacterial decomposition, and lightning Bacterial decomposition, and lightning

hitting Nhitting N22

COCO22 in the air forms carbonic acid in the air forms carbonic acid

COCO22 + H + H22O O H H22COCO33

This increases the [HThis increases the [H++]] of rain of rain

HH22COCO33 H H++ (aq) + HCO (aq) + HCO33-(aq)-(aq)

Reactions with oxygen in air form SOReactions with oxygen in air form SO33

2SO2SO22 + O + O22 2 SO 2 SO33

Reactions with water in air form acidsReactions with water in air form acids

SOSO33 + H + H22O O HH22SOSO44 sulfuric acid sulfuric acid

NO + HNO + H22O O HNOHNO22 nitrous acid nitrous acid

HNOHNO22 + H + H22O O HNOHNO33 nitric acid nitric acid

Effects of Acid RainEffects of Acid Rain

Effects of Acid RainEffects of Acid Rain

Leaches heavy metals like Al from soil, Leaches heavy metals like Al from soil,

which kills fishwhich kills fish

Fish kills in spring from runoff due to Fish kills in spring from runoff due to

accumulation of large amounts of acid accumulation of large amounts of acid

in snow in snow

Dissolves waxy coatings that protect Dissolves waxy coatings that protect

leaves from bacterialeaves from bacteria

Corrodes metals, textiles, paper and Corrodes metals, textiles, paper and

leatherleather

Acid Rain Destroys National MonumentsAcid Rain Destroys National Monuments

http://news.discovery.com/videos/earth-acid-http://news.discovery.com/videos/earth-acid-rain-eating-washington-dc.htmlrain-eating-washington-dc.html

Global Warming: COGlobal Warming: CO22 and Ocean Acidity and Ocean Acidity

http://planetgreen.discovery.com/videos/http://planetgreen.discovery.com/videos/blue-august-acid-in-the-water.htmlblue-august-acid-in-the-water.html

Acid Rain Site produced by EPAAcid Rain Site produced by EPAhttp://www.epa.gov/acidrain/education/http://www.epa.gov/acidrain/education/

site_kids/site_kids/

EPA Website Detailing Acid Rain Causes EPA Website Detailing Acid Rain Causes and Effects as well as Legislationand Effects as well as Legislation

http://www.epa.gov/acidrain/http://www.epa.gov/acidrain/

Neutralization Neutralization ReactionsReactions

General ReactionGeneral Reaction

Neutralization Forms WaterNeutralization Forms Water

HH++ + OH + OH-- H H22OO

from acid from basefrom acid from base neutral neutral

This “net” reaction for neutralization is foundThis “net” reaction for neutralization is found

on Table I. It is an exothermic reaction. on Table I. It is an exothermic reaction.

Forming a SaltForming a Salt

(+) cation(+) cation from the base, from the base,

(-) (-) anionanion from the acid from the acid combine to form a salt.combine to form a salt.

HCl + NaOH NaCl + HOHHCl + NaOH NaCl + HOH

Acid + Base Salt + waterAcid + Base Salt + water

Neutralization ReactionsNeutralization Reactions

These are double replacement reactionsThese are double replacement reactions

Ions switch partners. Water is formed.Ions switch partners. Water is formed.

Neutralization ReactionsNeutralization Reactions

If If equal concentrationsequal concentrations of hydrogen ion H of hydrogen ion H++ and and hydroxide ions OHhydroxide ions OH-- are mixed, it results in a are mixed, it results in a neutral solution.neutral solution.

Ex:Ex:.1M LiOH + .1M HCl = Neutral Solution.1M LiOH + .1M HCl = Neutral Solution

Completing and Balancing and Completing and Balancing and NamingNaming

Write charges for ions in acid and base.Write charges for ions in acid and base.Switch ion partners. (+ ions stay in front!!)Switch ion partners. (+ ions stay in front!!)Do not bring over subscripts except if part Do not bring over subscripts except if part

of a polyatomic ion!of a polyatomic ion!Criss-Cross charges to balance formulas.Criss-Cross charges to balance formulas.Balance entire equation.Balance entire equation.Name the acid, base and salt.Name the acid, base and salt.

You Try ItYou Try It

Complete and balance formulas and Complete and balance formulas and equation.equation.

Name acid base and saltName acid base and salt

Ex:Ex: KOH + HKOH + H22SOSO44

Ex: Mg(OH)Ex: Mg(OH)22 + HNO + HNO33

TitrationsTitrations

Purpose:Purpose:

To determine the concentration of an acid To determine the concentration of an acid or base through a neutralization reaction.or base through a neutralization reaction.

Acid/Base TitrationAcid/Base Titration

Buret is filled with aBuret is filled with a

““standard solutionstandard solution” of” of

known concentration.known concentration.

Erlenmeyer Flask containsErlenmeyer Flask contains

solution of solution of unknown unknown conc..conc..

Indicator (phenolphthalein)Indicator (phenolphthalein)

added to the flask.added to the flask.

Acid/Base TitrationsAcid/Base Titrations

Slowly “titrate” or drip liquidSlowly “titrate” or drip liquid

into flask from buret untilinto flask from buret until

indicator changes color. indicator changes color.

This is the “This is the “endpointendpoint”.”.

Record total volume usedRecord total volume used

from buret.from buret.

Titration FormulaTitration Formula

MMA x V x VA = M = MB x V x VB

Molarity Acid x Volume Acid = Molarity Base x Volume Base

At “equivalence point”

Moles H+ = Moles OH-

Important NoteImportant Note

Multiply acid/base side of equation by Multiply acid/base side of equation by number of Hnumber of H++ or OH or OH-- ions it produces when ions it produces when dissociating!!!dissociating!!!

Ex: Ex:

HH22SOSO44 produces 2 H produces 2 H++ so you would so you would

multiply the acid side by “2”multiply the acid side by “2”

You Try It!You Try It!

A 50 ml sample of .2M HCl is neutralized byA 50 ml sample of .2M HCl is neutralized by

75ml of NaOH. What is the conc. of the base?75ml of NaOH. What is the conc. of the base?

HClHCl NaOHNaOH

.2M x 50ml = M.2M x 50ml = MBB x 75ml x 75ml

MMBB = .13M = .13M

You Try It!You Try It!

How much of a .1M HHow much of a .1M H22SOSO44 solution is solution is

needed to neutralize 50 ml of a .05 KOHneeded to neutralize 50 ml of a .05 KOHsolution?solution?

HH22SOSO44 KOHKOH

2 x .1M x V2 x .1M x VA A = .05M x 50ml = .05M x 50ml

VVAA = 12.5 ml = 12.5 ml

Titration AppletTitration Applet

http://group.chem.iastate.edu/Greenbowe/http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/sections/projectfolder/flashfiles/stoichiometry/acid_base.htmlstoichiometry/acid_base.html

HydrolysisHydrolysis

Opposite reaction to neutralizationOpposite reaction to neutralization

Salt + Water Salt + Water Acid + BaseAcid + Base

Parent Acid/BaseParent Acid/Base

If you know the salt involved you should If you know the salt involved you should be able to determine which acid and base be able to determine which acid and base it would form if water is added.it would form if water is added.

Salt + Water Salt + Water Acid + BaseAcid + Base

Ex: Ex:

NaCl with water (HOH) would form HCl and NaOHNaCl with water (HOH) would form HCl and NaOH

You Try ItYou Try It

Name the “parent” acid and base that Name the “parent” acid and base that would be produced from these salts.would be produced from these salts.

Ex:Ex: Potassium chloridePotassium chloride

Magnesium carbonateMagnesium carbonate

pH and HydrolysispH and Hydrolysis

Salts can yield neutral, acidic or basic Salts can yield neutral, acidic or basic solutions depending on what type of acid solutions depending on what type of acid or base they produce.or base they produce.

SA/SB = NeutralSA/SB = Neutral

SA/WB = AcidicSA/WB = Acidic

WA/SB = BasicWA/SB = Basic

WA/WB = UndeterminedWA/WB = Undetermined

Strength of Strength of Acids and BasesAcids and Bases

Do they ionize 100%?Do they ionize 100%?

Strong Acids :Strong Acids : Give up HGive up H++ easily easily

Dissociate completely (100%) in waterDissociate completely (100%) in water

HCl, HBr, HI, HNOHCl, HBr, HI, HNO33, H, H22SOSO44, HClO, HClO44, HClO, HClO33

Weak acids: (all others)Weak acids: (all others)Hold onto HHold onto H++

Few molecules dissociateFew molecules dissociate

Ex: HCEx: HC2HH33OO2 2

HA

Let’s examine the behavior of an acid, HA, in aqueous solution.

What happens to the HA molecules in solution?

HA

H+

A-

Strong Acid

100% dissociation of HA

Would the solution be conductive?

Oh yeah…

HA

H+

A-

Weak Acid

Partial dissociation of HA

Would the solution be conductive?

Not really…

HA

H+

A-

Weak Acid

HA H+ + A-

At any one time, only a fraction of

the molecules

are dissociated.

Acids Ionizing in Water (Strong vs. Weak)Acids Ionizing in Water (Strong vs. Weak)

http://youtu.be/kcPjY9cQpWshttp://youtu.be/kcPjY9cQpWs

Acid H Transfer (Strong vs. Weak)Acid H Transfer (Strong vs. Weak)

http://preparatorychemistry.com/http://preparatorychemistry.com/acids_flashhtmacids_flashhtm

Strong BasesStrong Bases: : Dissociate completely (100%) in waterDissociate completely (100%) in water

- Group I metal hydroxides (NaOH, LiOH, etc.)- Group I metal hydroxides (NaOH, LiOH, etc.)

- Some Group II metal hydroxides- Some Group II metal hydroxides

Ca(OH)Ca(OH)22, Ba(OH), Ba(OH)22, ,

Sr(OH)Sr(OH)22

Weak BasesWeak Bases

Only a few ions dissociateOnly a few ions dissociate

Ex: NHEx: NH 3 3 (ammonia) (ammonia)

Strength and ReactivityStrength and Reactivity Acids/bases of the same initial molar Acids/bases of the same initial molar

concentration can react differently and conduct concentration can react differently and conduct electricity differently if one is weak and the other electricity differently if one is weak and the other strong.strong.

Ex: Ex: 2M HCl = 2M HCl = Strong Acid, Strong Acid, very conductive very conductive

very reactivevery reactive

2M 2M HCHC22HH33OO2 2 = Weak Acid = Weak Acid

Weak ConductionWeak ConductionSalad Dressing!!!Salad Dressing!!!

The BrThe Brøønsted-Lowry Definition nsted-Lowry Definition of Acids and Basesof Acids and Bases

Acid:Acid: PROTON DONOR PROTON DONOR

can donate Hcan donate H++ ions. ions.

Base:Base: PROTON ACCEPTORPROTON ACCEPTOR

acceptsaccepts HH++ ions. ions.

Broader Definition than ArrheniusBroader Definition than Arrhenius

Review: Arrhenius Definition of Review: Arrhenius Definition of Acids and BasesAcids and Bases

Acids produce HAcids produce H++ in aqueous (water) solutions in aqueous (water) solutions waterwater

HCl HCl H H+ + (aq) + Cl(aq) + Cl- - (aq)(aq)

Bases produce OHBases produce OH-- in aqueous (water) solutions in aqueous (water) solutions

waterwater

NaOHNaOH Na Na+ + (aq) + OH(aq) + OH- - (aq)(aq)

HH++ Transfer Transfer

Acid/base reactions involve Acid/base reactions involve ““proton transferproton transfer”.”.

The reaction need not occur in water.The reaction need not occur in water.

HH++ leaves one compound and is leaves one compound and is transferred to another.transferred to another.

Ex: Ex: NHNH33 + H + H22O O NHNH44++ + +

OHOH--

BaseBase AcidAcid

Conjugate acid/base pairs:Conjugate acid/base pairs: formulas differformulas differ

by only a hydrogen ion, Hby only a hydrogen ion, H++..

The acid on one side becomes the base onThe acid on one side becomes the base on

the other side and vice versa.the other side and vice versa.

Ex: Ex:

HCl + HHCl + H22O O HH33OO++ + Cl + Cl--

AcidAcid Base Base AcidAcid Base Base

Conjugate acidConjugate acid

contains onecontains one

more Hmore H++ in its in its

formulaformula

Amphoteric/Amphiprotic Substances:Amphoteric/Amphiprotic Substances:

Can act as either an acid or a base.Can act as either an acid or a base.

Must have an “H” in formula (to donate)Must have an “H” in formula (to donate)

Must have a free eMust have a free e-- pair (to accept a H pair (to accept a H++))

Water is amphotericWater is amphoteric It can donate an HIt can donate an H++

or accept an Hor accept an H++.. It depends on what it It depends on what it

is combined with.is combined with.

Water Water donates Hdonates H++

to NHto NH33 forming the hydroxide ion (OH forming the hydroxide ion (OH--). ).

Water Water acceptsaccepts HH++

from HCl forming the hydronium ion (Hfrom HCl forming the hydronium ion (H33OO++).).

When life goes either wayamphoteric (amphiprotic) substances

HCO3-

H2CO3 CO3-2

+ H+ - H+

Acting like a base

Acting like an acid

accepts H+ donates H+

Dilution

water (solvent) solute

concentrated, Minitial

diluted, Mfinal

adding water lowers the solute concentration

moles of solute remain constant

Vinitial

Vfinal

molesinitial = molesfinal

Mfinal x Vfinal = Minitial x Vinitial

Titration AppletTitration Applethttp://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/

acid_base.htmlacid_base.html

Strong/Weak Acid AnimationStrong/Weak Acid Animationhttp://educypedia.karadimov.info/library/acid13.swfhttp://educypedia.karadimov.info/library/acid13.swf

Acid dissociation in waterAcid dissociation in water http://www.chembio.uoguelph.ca/educmat/chm19104/chemtoons/chemtoons2.htmhttp://www.chembio.uoguelph.ca/educmat/chm19104/chemtoons/chemtoons2.htm

Acid/Bases TheoriesAcid/Bases Theories http://web.fccj.org/~ethall/acidbase/acidbase.htmhttp://web.fccj.org/~ethall/acidbase/acidbase.htm

Titration GameTitration Game http://www.sciencegeek.net/Shockwave/Titration.htmhttp://www.sciencegeek.net/Shockwave/Titration.htm

Acid Bases Hydrogen Transfer (Neutralization)Acid Bases Hydrogen Transfer (Neutralization) http://preparatorychemistry.com/neutralization_flash.htmhttp://preparatorychemistry.com/neutralization_flash.htm