Taste sourTaste sour Form solution that conduct Form solution that conduct

electricityelectricity React with metalsReact with metals Turn blue litmus paper to redTurn blue litmus paper to red React with bases to form salt React with bases to form salt

and waterand water Ex: fruit juice, vinegar, milkEx: fruit juice, vinegar, milk

Form solutions that conduct Form solutions that conduct electricityelectricity

Slippery or soapy in the skinSlippery or soapy in the skin Taste bitterTaste bitter Turn red litmus paper to blueTurn red litmus paper to blue Reacts with acids to form salt and Reacts with acids to form salt and

water water Ex: soap, shampoo, cleaning agentEx: soap, shampoo, cleaning agent

Arrhenius TheoryArrhenius Theory

By Svante August ArrheniusBy Svante August Arrhenius Acids form hydrogen ion(H+) in Acids form hydrogen ion(H+) in

aqueous solutionsaqueous solutions Bases form hydroxide ion (OH-)Bases form hydroxide ion (OH-) in aqueos solutionin aqueos solution Ex:Ex: HCl(g)-----> H HCl(g)-----> H++(aq) + Cl(aq) + Cl--(aq)(aq) KOH -----> KKOH -----> K++ + OH + OH--(aq)(aq)

Bronsted-Lowry DenitionBronsted-Lowry Denition

By Johannes Bronsted and By Johannes Bronsted and Thomas LowryThomas Lowry

Acid is a proton donorAcid is a proton donor Base is a proton acceptorBase is a proton acceptor Ex:Ex: HCl + HHCl + H22O ---> HO ---> H33O + Cl-O + Cl- NHNH33 + H + H22O O

Bronsted-Lowry DefinitionBronsted-Lowry Definition

The general reaction when an acid is The general reaction when an acid is dissolved in water is best represented by dissolved in water is best represented by an acid donating Han acid donating H++ to water molecule to to water molecule to form a new acid (conjugate acid) and a form a new acid (conjugate acid) and a new base( conjugate base)new base( conjugate base)

acid base conjugate Conjugate acid base conjugate Conjugate . Acid . Acid basebase

HAHA(aq)(aq) + H + H2200(l)(l) ----> H ----> H33OO++(aq)(aq) + A + A--

(aq)(aq)

Ex:Ex:

HCl + HHCl + H22O ---> HO ---> H33OO++ + Cl + Cl-- acid base conjugate conjugateacid base conjugate conjugate

acid baseacid base

Identify the acid and the base Identify the acid and the base in the following reactions:in the following reactions: HSOHSO44

- - + PO+ PO443-3- ---> HO ---> HO44

2-2- + SO + SO442-2-

HNOHNO33 + H + H22O ---> HO ---> H33O O ++ + NO + NO3-3-

HH33POPO44 + CN + CN-- ---> H ---> H22POPO44-- + HCN + HCN

AnswersAnswers Acid baseAcid basea)a) HSOHSO44

-- PO PO443-3-

b)b) HNOHNO33 H H22OO

c)c) HCN HHCN H22POPO44--

Conjugate Acid-base pairConjugate Acid-base pair

Consists of two substances related to each Consists of two substances related to each other by donating and accepting of a single other by donating and accepting of a single protonproton

Acid-conjugate base pairAcid-conjugate base pair

Ex: HCl(aq) + HEx: HCl(aq) + H22O(l) O(l) H H33OO++ + Cl + Cl--

Base-conjugate acid pairBase-conjugate acid pair

HH33OO++ --> hydronium ion --> hydronium ion

Which of the following represent Which of the following represent Conjugate acid-base pair?Conjugate acid-base pair? A) HF, FA) HF, F--

B) NHB) NH44++, NH, NH33

C) HCl, HC) HCl, H22OO AnswerAnswerA and B are conjugate acid base pair A and B are conjugate acid base pair

because they differ by one H+because they differ by one H+C is not because the conjugate acid-base pair C is not because the conjugate acid-base pair

of HCl is Cl-of HCl is Cl-

Writing Conjugate BasesWriting Conjugate Bases

Write the conjugate base for Write the conjugate base for each of the following:each of the following:

a) HClOa) HClO44

HClOHClO44 ----> H ----> H++ ClO ClO44--

conjugate baseconjugate base

b) Hb) H33POPO44

HH33POPO44 H H++ H H22POPO44

conjugate baseconjugate base

Practice: ClassworkPractice: Classwork

Which of the following represent conjugate Which of the following represent conjugate acid-base pair?acid-base pair?

A) HClOA) HClO44, ClO, ClO44--

B) HCl, ClOB) HCl, ClO--

C) HC) H22POPO44--, HPO, HPO44

2-2-

D) HNOD) HNO33, NO, NO3-3-

Write the conjugate base for each of the ff:Write the conjugate base for each of the ff:a)a) HH22SS

b)b) NHNH33

c)c) HH22SOSO33

AnswerAnswer

Which of the following represent conjugate Which of the following represent conjugate acid-base pair?acid-base pair?

A) HClOA) HClO44, ClO, ClO44- -

B) HCl, ClOB) HCl, ClO--

C) HC) H22POPO44--, HPO, HPO44

2- 2-

D) HNOD) HNO33, NO, NO3- 3-

Write the conjugate base for each of the ff:Write the conjugate base for each of the ff:a)a) HH22S S HS HS--

b)b) NHNH3 3 NH NH22--

c)c) HH22SOSO33 HSO HSO33--

Lewis TheoryLewis Theory Gilbert LewisGilbert Lewis Chemical reactions involve the Chemical reactions involve the

arrangement of the valence arrangement of the valence electrons of an atom.electrons of an atom.

Acid is an electron pair acceptorAcid is an electron pair acceptor Base is an electron pair donorBase is an electron pair donor HH22O + NHO + NH33 H H H H ++

H-O-H + : N H ---> H-N-H + OHH-O-H + : N H ---> H-N-H + OH--

H HH HLewis Acid Lewis Base Lewis Acid Lewis Base

Ex: reaction between BClEx: reaction between BCl33 and NH and NH33

Cl H Cl H Cl – B + : N –H ---> Cl –B – N –H

Cl H Cl H Lewis Lewis Lewis acid-base acid base adduct

Adduct is the term used for the product of the Lewis Acid-base reaction

Strong AcidsStrong Acids

Bronsted-Lowry definition is useful in Bronsted-Lowry definition is useful in describing the strength of an aciddescribing the strength of an acid

Strong acid is one that dissociates or Strong acid is one that dissociates or ionizes completely in waterionizes completely in water

Ex:HCl + HEx:HCl + H22O O H H33OO++ + Cl + Cl--

Forward reaction predominates which Forward reaction predominates which indicates ionization is completeindicates ionization is complete

Strong acid contains a Strong acid contains a weak conjugate weak conjugate basebase weaker than water weaker than water

Weak AcidWeak Acid

It does not completely dissociate or ionize.It does not completely dissociate or ionize. Ex: Acetic Acid( CHEx: Acetic Acid( CH33COOH)COOH)

CHCH33COOH + HCOOH + H22O HO H3300++ + CH + CH33COOCOO--

acetate ionacetate ion

The two arrows indicate that the ionization The two arrows indicate that the ionization is not completeis not complete

The reverse reaction predominates that The reverse reaction predominates that means only few ions are dissociatedmeans only few ions are dissociated

Weak acidWeak acid contains relatively contains relatively strong strong conjugate baseconjugate base

Strong BasesStrong Bases

Common strong bases are those that Common strong bases are those that contain the hydroxide ion contain the hydroxide ion

Ex:Ex:,NaOH,KOH Mg(OH),NaOH,KOH Mg(OH)22, Ca(OH)2, Ca(OH)2

Ba(OH)Ba(OH)22

Very soluble in waterVery soluble in water

Weak BasesWeak Bases

The strengths of bases that do not The strengths of bases that do not have OHhave OH-- are described in the same are described in the same way that the strengths of the acids way that the strengths of the acids were describedwere described

Weak base does not completely Weak base does not completely dissociate in waterdissociate in water

Ex: NHEx: NH33 + H + H22O NHO NH44++ + OH- + OH-

reverse reaction predominatesreverse reaction predominates

Show the ionization of HShow the ionization of H22SOSO44 and NaOHand NaOH

H2OH2O

HH22SOSO44(l) ----> H(l) ----> H++(aq)(aq) + SO + SO44

2-2-(aq)(aq)

2H2H++(aq)(aq) + SO + SO44

2-2-(aq)(aq)

H2OH2O

NaOH ------> NaNaOH ------> Na++ + OH + OH--

Acid StrengthAcid Strength

StrongStrongAcidAcid

StrongStrongBaseBase

Moderate Moderate AcidAcid

WeakWeakAcidAcid

Weak Weak BaseBase

HClOHClO44

Perchloric acidPerchloric acid

NaOHNaOH HH33POPO44

Phosphoric acidPhosphoric acid

CHCH33COOHCOOH NH3NH3

HClOHClO33

Chloric AcidChloric Acid

KOHKOH ModerateModerateBaseBase

HH22COCO33 HCO3-HCO3-

HIHI Mg(OH)2Mg(OH)2 COCO332-2- HH33BOBO33 CH3COO-CH3COO-

HBrHBrHydrobromicHydrobromic

Ca(OH)2Ca(OH)2 CHCH33COOHCOOH SOSO442-2-

HH22SOSO44

Sulfuric acidSulfuric acid

Ba(OH)2Ba(OH)2 Very WeakVery WeakAcidAcid

Very WeakVery Weak BaseBase

HClHClHydrochloricHydrochloric

HH22OO HH22OO

HNOHNO33

Nitric AcidNitric Acid

Water as an acid and a baseWater as an acid and a base

Amphoteric substanceAmphoteric substance A substance that can behave either as an A substance that can behave either as an

acid or a baseacid or a base Ionizaton of waterIonizaton of water HH22O(l) + HO(l) + H22O(l) ---> HO(l) ---> H33OO++(aq) + OH(aq) + OH--(aq)(aq) The forward reaction is not greatThe forward reaction is not great In pure water only a tiny amount of HIn pure water only a tiny amount of H33OO++

and OHand OH-- is present. is present. [H[H33OO++] = [OH] = [OH--] = 1.0x10] = 1.0x10-7-7MM

The product of the HThe product of the H33OO++ and OH and OH-- concentrations is always constant at 25concentrations is always constant at 2500CC

[H[H33O] [OHO] [OH--] = 1x 10 ] = 1x 10 -14-14

(1x 10(1x 10-7 -7 ) ( 1 x 10) ( 1 x 10-7-7) = 1 x 10) = 1 x 10-14-14

This is called the This is called the ion product constantion product constant of water ( of water ( KwKw)) Note the product of HNote the product of H33O and OHO and OH-- in any aqueous is in any aqueous is

constant which means when [OHconstant which means when [OH--] goes up the [H3O] ] goes up the [H3O] must go downmust go down

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

Ex : calculate [HEx : calculate [H++] or [OH] or [OH--] as required for ] as required for each of the following at 25each of the following at 2500C and state C and state whether the solution is acidic, basic and whether the solution is acidic, basic and neutralneutral A) 1.0x10A) 1.0x10-5-5M OHM OH--

Given: [OHGiven: [OH--] = 1x10] = 1x10-5-5

Find: HFind: H++

Solution: [HSolution: [H++] [OH] [OH--] = 1x10] = 1x10-14-14

[H[H++] = ] = 1x101x10-14-14

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

[ 1x10[ 1x10-5-5]]

= = 1x 101x 10-9-9 M MSince OHSince OH-- = 1x10 = 1x10-5-5M M H+ = 1x10H+ = 1x10-9-9MMThe solution is basic since OHThe solution is basic since OH- - > H> H++

b) 10.0M Hb) 10.0M H++

Find: OHFind: OH--

Solution: [HSolution: [H++][OH][OH--] = 1 x10] = 1 x10-14-14

[OH[OH--] = ] = 1x 101x 10-14-14

10.0M10.0M = 1x 10-15M= 1x 10-15M [OH[OH--] = 1x10] = 1x10-15-15

[H[H++] = 1x 10] = 1x 1011MM[H[H++] > [OH] > [OH--] = the solution is acidic] = the solution is acidic

1. Which is greater [OH-] or [H+] , if 1. Which is greater [OH-] or [H+] , if [H+]= 2.8x 10-5M an aqueous solution at [H+]= 2.8x 10-5M an aqueous solution at

252500C?C?2. How many times greater is [OH-] than [H+] 2. How many times greater is [OH-] than [H+]

if [H+] = 1.0x 10-9 M in aqueous solution if [H+] = 1.0x 10-9 M in aqueous solution at 250C?at 250C?

3. Calculate the [H+] or [OH-] as required for 3. Calculate the [H+] or [OH-] as required for each of the following at 250C and state each of the following at 250C and state whether the solution is neutral, acidic or whether the solution is neutral, acidic or basic.basic.

a)a) [H+] = 3.4 x 10[H+] = 3.4 x 10-4-4MMb)b) [H+] = 2.6x 10[H+] = 2.6x 10-8-8MMc)c) [OH-] = 6.2 x 10[OH-] = 6.2 x 10-9-9MM

The pH ScaleThe pH Scale Was proposed by Soren SorensenWas proposed by Soren Sorensen ( Danish biochemist)( Danish biochemist) pH means power of hydrogenpH means power of hydrogen Has a range from 0 to 14 and is logarithmicHas a range from 0 to 14 and is logarithmic which means that each step is ten times the which means that each step is ten times the

previouspreviousEx: pH of 5 is ten times more acid than 6Ex: pH of 5 is ten times more acid than 6 What about pH 5 and 7What about pH 5 and 7---> pH 5 is 100times more acid than 7---> pH 5 is 100times more acid than 7What about pH 5 and 8?What about pH 5 and 8? 1000 times acidic1000 times acidic

pH scalepH scale

0-most acidic and 14 is most basic0-most acidic and 14 is most basic

0 1 2 3 4 5 6 7 8 9 10 11 12 13 140 1 2 3 4 5 6 7 8 9 10 11 12 13 14 At pH-7, water has equal amount of HAt pH-7, water has equal amount of H++ and and

OHOH-- ions ions[H+] = [OH-] [H+] = [OH-] neutral neutral[H+] > [OH-][H+] > [OH-] acidic acidic[H+] < [OH-][H+] < [OH-] basic basic

pH of a solutionpH of a solution

Defined is the negative of the logarithm Defined is the negative of the logarithm of the hydronium ion concentration, of the hydronium ion concentration, [H[H33OO++]]

pH = - log [HpH = - log [H33O+]O+]Ex: Pure water has [HEx: Pure water has [H33OO++]= 1x10]= 1x10-7-7M. Find M. Find

pHpH pH = -log[HpH = -log[H33OO++] ] pH = -log[ 1x10pH = -log[ 1x10-7-7M]M] pH = - (-7)pH = - (-7) pH = 7pH = 7

In Basic solution, In Basic solution, [OH-] can be expressed as pOH[OH-] can be expressed as pOH pOH = -log [OHpOH = -log [OH--]]Recall that [HRecall that [H33OO++] [OH] [OH--] = 1 x 10 ] = 1 x 10 -14-14

Using the definition of pH and pOH the Using the definition of pH and pOH the equation can be translated asequation can be translated as

pH + pOH = 14pH + pOH = 14In summary,In summary,pH= -log[HpH= -log[H33OO++]]pOH = -log [OHpOH = -log [OH--]][H[H33OO++][OH][OH--] = 1x10] = 1x10-14-14

pH + pOH = 14pH + pOH = 14

In Pure water, the concentrations of HIn Pure water, the concentrations of H33OO++ and and OHOH- - are equalare equal

[H3O[H3O++] = [OH-] = 1x10] = [OH-] = 1x10-7-7M thusM thus pH and pOH are also equalpH and pOH are also equalpH = pOH = 7pH = pOH = 7pH + pOH = 14pH + pOH = 147 + 7 = 147 + 7 = 14

Ex:Ex:

Find the pH and pOH of 0.001MHCl Find the pH and pOH of 0.001MHCl solutionsolution

Given: [HGiven: [H33OO++] = 0.001M ] = 0.001M Find a) pH b) pOHFind a) pH b) pOH SolutionSolution A) pH = -log [HA) pH = -log [H33OO++]] = -log [ 1x10= -log [ 1x10-3-3] = -(-3)] = -(-3) = 3= 3 B) pH + pOH = 14B) pH + pOH = 14 pOH = 14 - pHpOH = 14 - pH = 14 - 3= 14 - 3 1111

Ex2:Ex2:

If the OH- is equal to 0.00001M, Find the pHIf the OH- is equal to 0.00001M, Find the pHSolution: Get the pOH firstSolution: Get the pOH firstpOH=-log[OH-]pOH=-log[OH-] = -log(10= -log(10-5-5M)M) = -(-5)= -(-5)pOH = 5pOH = 5Get the pH Get the pH pH +pOH = 14pH +pOH = 14pH = 14 – pOHpH = 14 – pOH = 14 – 5= 14 – 5pH = 9pH = 9

Class workClass work A solution has a HA solution has a H33O+ concentration equal to 5.5x O+ concentration equal to 5.5x

1010-8-8M. What is the pH of the solution?M. What is the pH of the solution? The pH of rainwater in a locality is 3. What is the The pH of rainwater in a locality is 3. What is the

[H[H33OO++]?]? What is the [HWhat is the [H++] of a solution with a pH of 4.2?] of a solution with a pH of 4.2? The pOH of blood is 6.6. What is the pH of the The pOH of blood is 6.6. What is the pH of the

blood?blood? Calculate the pH and pOH for each of the ff.Calculate the pH and pOH for each of the ff. A) a solution in which[H+] = 3.6 x 10A) a solution in which[H+] = 3.6 x 10-9-9MM B)[OH-] = 9.2 x 10-2MB)[OH-] = 9.2 x 10-2M The pH of the solution is 5.67. What is the pOH of The pH of the solution is 5.67. What is the pOH of

the solution?the solution?