7.0 Ionic Equilibria (Students)

8/16/2019 7.0 Ionic Equilibria (Students)

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1. Acids and bases

2. Acids-Base titration

3. Solubility equilibria

a) Define acid and base

b) Define and identify conjugate acids andconjugate base according to Bronsted-Lowryteory

c) Define

d) Define pH ! pOH

e) "elate #$ and #%$ to &w at 2'(

f) alculate #$ *alue of strong acid and base

g) "elate strengt of a wea+ acid and wea+ baseto te Ka and Kb (pKa,pKb,pKw,pH,pOH)

) ,erfor calculation #$! &a! &b! / 0! α)

i) # salt ydrolysis and write its equation

j) Define buffer solution

+) Describe ow buffer solution controls #$

l) Deri*e $enderson-$asselbalc equation

a) Describe titration #rocess

b) Distinguis between te end #oint andequi*alence #oint

c) S+etc and inter#ret te *ariation of #$ againtstitre *alue for titration between

i) strong acid-strong base

ii) strong acid-weak base

iii) weak acid-strong base

a) dentify suitable indicator for acid-base titration

a) Define

i) solubility

ii) molar solubility

iii) solubility product ,Ksp

b) alculate &s#

c) ,redict te #ossibility of #reci#itation of sligtlysoluble ionic co#ounds by co#aring te *alue of ion-#roduct! Q to Ksp

d) Define and e#lain te coon ion effect

e) ,erfor calculation related to coon ion effect

Arrhenius theory

Bronsted-owry theory

ewis theory

strong acid and strong base strong acid and weak base

weak acid and strong base

strong acid and base

weak acid and base

4.( %5 67LB"A%8"89



Learning outcoes: (1 hour)

At the end of this lesson , students should be able to:

Define acid and base according to Arrhenius, Bronsted-

Lowry and Lewis theories.

Define and identify conjugate acid and conjugate base

according to Bronsted- Lowry theory. Define strong acid and base, weak acid and base.



;e #$ of te gastric juice is about 1.'! wiccorres#onds to $l (.(3 !

a concentration strong enoug to dissol*e <inc etal=

9at is te #$ of te gastric juice in your stoac>



%5 67LB"7?

4.1 ;eory of Acids and Bases

9e generally classify acidsand bases as eiter strong or wea+! according to te etent of

teir dissociation into ions inwater.;e concentration of

/$@0 or /%$-0



5"AL ,"%,";S % ADS and BASS

ADS BASS

$a*e a sour taste $a*e a bitter taste

"eact wit acti*e etals suc as Al and Cn to#roduce $2 gas

ange color of litusfro blue to red

ange color of litusfro red to blue

Aqueous acid solutions

conduct electricity

Aqueous base solutions

conduct electricity

"eact wit carbonates and bicarbonates suc

as 5a2%3! a%3 and

5a$%3 to #roduce %2 gas

eel sli##ery



Acidbase definition:

Arrenius

BrEnstedLowry

Lewis teories

S*ante August Arrenius 1F'G-1G24). Swedis ceist.

Hoannes 5icolaus BrEnsted 1F4G-1GI4). Danis ceist.;oas ?artin Lowry 1F4I-1G3J)! nglis ceist.

ilbert 5ewton Lewis 1F4'-1GIJ). Aerican ceist.

9$A; S AD > 9$A; S BAS >



Acid: Substance tat as $ in its forula and

dissociates in water to yield $3%@

KA?,L:

Base: Substance tat as %$ in its forula

and dissociates in water to yield %$

KA?,L:

A""$57S ADBAS D5;%5

$5%3a" ) @ $2%l ) $3%@a" ) @ 5%3

a" )

$3%%$a" ) @ $2%l ) $3%% a" ) @ $3%@a" )

5a%$a" ) 5a@a" ) @ %$ a" )



Base: Any s#ecies tat acce#ts $@ #roton acce#tor )

B"5S;DL%9"M ADBASD5;%5

;e definition focus on #roducts and reactants

acidbase reaction)

5$3a" ) @ $2%l ) 5$I@a" ) @ %$ a" )

acid conjugatebase

base conjugateacid

Acid: Any s#ecies tat donates $@

#roton donor )

$3%%$a" ) @ $2%l ) $3%% a" ) @ $3%@a" )

KA?,L:

acid conjugate

base

base conjugate

acid

KA?,L:



*ery acid as a conjugate base

*ery base as a conjugate acid

BAS-%5H7A; AD ,A"

$3%%$a" ) @ 5 a" ) $3%% a" ) @ $5a" )

acid base conjugatebase

conjugateacid

Acid: #roton donor

Base: #roton acce#tor



Acid: Any s#ecies tat acce#ts an electron #air

KA?,L: B3 ! All3 ! S%2 ! %2 ! 5a@

KA?,L: 5$3! $3l! $3%$3! $2%! %2

Base: Any s#ecies tat donates an electron #air

A @ :B

L9S ADBAS D5;%5

ANB

acid base

new co*alent bond



ontains a central ato tat is electron deficient inco#lete octet

KA?,L:●●

B

●●

●●

●●

●●

●●

●●

●●

●●

5 $

$

$●●

B

●●●

●●●

●●●●

●●

●●●●

●●

5 $

$

$

acid base

L9S ADS 9;$L;"%5 D5; A;%?S



;able J.1 : a#les of Lewis acids and bases

Lewis acid Lewis base

(a) ositi!e ions

e.g : "# , $e%# , Al&#

(a) 'egati!e ions

e.g : "- , '- , l-

(b) *olecules with an inco+leteoctet of electrons.

e.g : B$& , Bel% , Bl&

(b) *olecules with lone air ofelectrons.

e.g : "% , '"& , "



dentify te conjugate acidbase #airs:a) $%%$a" ) @ $2%l ) $%% a" ) @ $3%

@a" )

b) $2%l ) @ a" ) %$ a" ) @ $a" )

c) $2,%I a" ) @ %3

2 a" ) $%3 a" ) @ $,%I

2 a" )

d) $2%l ) @ S%32 a" ) %$ a" ) @ $S%3

a" )

EXAMPLE



Ans: EXAMPLE

a) $%%$a" ) @ $2%l ) $%% a" ) @ $3%@a" )

b) $2%l ) @ a" ) %$ a" ) @ $a" )

A O acid

cA O conjugate acid

B O base

cB O conjugate base



Ans: EXAMPLE

c) $2,%I a" ) @ %32 a" ) $%3 a" ) @ $,%I2 a" )

d) $2%l ) @ S%32 a" ) %$ a" ) @ $S%3

a" )

A O acid

cA O conjugate acid

B O base

cB O conjugate base



Dissociate co#letely 1(( P! α O 1.() into ions

in water

$Al ) @ $2%l ) $3%@a" ) @ A a" )

Ka etreely large

S;"%5 AD

$ydroalic acids: $l! $Br and $

%oacids: $5%3! $2S%I and $l%I

$5%3a" ) @ $2%l ) $3%@a" ) @ 5%3

a" )

KA?,L:



Dissociate *ery sligtly α Q 1.() into ions in water

K a *ery sall

$Aa" ) @ $2%l ) $3%@a" ) @ A a" )

$5a" ) @ $2%l ) $3%@a" ) @ 5 a" )

KA?,L:

9A& AD

%oacids: $l%! $5%2 and $3,%I

%rganic acids: $3%%$ and J$'%%$

$ydroalic acids: $

%ter: $5 and $2S



Dissociate co#letely 1(( P) into ions in water

K b etreely large

S;"%5 BAS

?2% or ?%$:

?% or ?%$)2:

Soluble co#ounds containing %2 or %$

?: rou# 1) etal Li! 5a! &! "b! s)

?: rou# 2) etal a! Sr ! Ba)

KA?,L:

5a%$a" ) 5a@a" ) @ %$ a" )



Dissociate *ery sligtly into ions in water

K b *ery sall

5$3g ) @ $2%l ) 5$I@a" ) @ %$ a" )

KA?,L:

9A& BAS

?olecules wit an 5 ato tat as a lone#air electrons:

5$3 ..



lassify eac of te following co#ounds asa strong acid! wea+ acid! strong base! or wea+ base! or s#ecies wit negligible acidity.

a) $3

)2

$%%$

b) &%$c) $3)2$5$2

d) $5%2

e) $2S%I

f) $,%I2

g) $I

) $35$3

@

EXAMPLE



Ans: EXAMPLE

a) $3)2$%%$

b) &%$

c) $3)2$5$2

d) $5%2

e) $2S%I

f) $,%I2

g) $I

) $35$3@



Define #$ and #%$

"elate #$ and #%$ to te ionic #roduct ofwater! K w at 2'(

alculate te #$ *alues of a strong acidand base.



4.1.I: #$ and #%$

#%$ is defined as te negati*e logarit log) ofte ydroide ion.

#$ is defined as te negati*e logarit log) of

te ydroniu!$3%@

concentration. /$3%

@0 in a solution is easured using

#$ scale etod.

#$ O - log /$@0

∴

f /$@0↑

! #$↓

.

concentration of %$- is easured using #%$.

#%$ O - log /%$-0

∴

f /%$-

0↑

! #$ ↑

! #%$ ↓



#$ O log /$3%

@

0#%$ O log /%$ 0

#$ SAL

;e iger /$3%@0! te lower #$

;e iger te /%$ 0! te lower #%$



Acidbase indicator

#$ #a#er R color cart)

#$ eter

#$ ?AS7"?5;

#$ of a neutral solution O 4.(

#$ of an acidic solution Q 4.(

#$ of an basic solution 4.(



9ater dissociates into ions *ery sligtly

/ $3%@

0 / %$

0K 9 O

O 1.( 1( 1I at 2'o)

n #ure water at 2'oT

K 9 : ion #roduct constant for water

A7;%%5CA;%5 % 9A;"

$2%l ) @ $2%l ) $3%@a" ) @ %$ a" )

/$3%@0 O /%$ 0 O 1.( 1( 4 ?



"elationsi# between K w! #$ and #%$ at 2'o!

/$@0 /%$-0 O K w

-log bot side! -log /$@0 /%$-0) O -log K

w-log /$@0 @ log /%$-0) O - log 1.( 1(-1I)

#$ @ #%$ O #K w

#$ @ #%$ O 1I



A cange in /$3%0@

causes an in*erse cangein /%$ 0

$iger /$3%@0 lower /%$ 0

$iger /%$ 0 lower /$3%@0

Bot ions are #resent in all aqueous systes

n acidic solution! /$3%@0 /%$ 0

n basic solution! /$3%@0 Q /%$ 0

n neutral solution! /$3%@0 O /%$ 0

/$3%@0 and /%$ 0

/$@0 /%$-0 O K w

AL7LA;5 /$ %@0 A5D /%$ 0



K 9 O / $3%@ 0 / %$ 0 O 1.( 1( 1I at 2'o)

/ $3%@ 0 O

K 9

/ %$

0

/ %$ 0 OK 9

/$3%@

0

AL7LA;5 /$3%@0 A5D /%$ 0

5 A67%7S S%L7;%5



#$ U #%$ S;"%5 ADS A5D BASS

Strong acids and bases are considered to be 1((P dissociated in an aqueous solution

KA?,L: Strong acid

$la" ) @ $2%l ) $3%@a" ) @ l a" )

before: (.(2( ! ( (

after: (( #$$% dissociated )

(.(2( ! (.(2( !

#$ O log /$3%@0

O 1.4(

O log /(.(2(0



KA?,L: Strong base

Ba%$)2a" ) Ba2@a" ) @ 2%$ a" )

before: (.(((3' ! ( (

after: (( #$$% dissociated ) (.(((3' ! (.(((4( !

#$ O log /$3%@0

O 1(.F'O log 1.I3 1( 11)

/ $3%@ 0 O K 9

/%$ 0

O1.( 1( 1I

(.(((4(O 1.I3 1( 11 !

#$ U #%$ S;"%5 ADS A5D BASS



EXAMPLE

a) 9at is te #$ of a (.(I( ! solution of $l%I >

b) An aqueous solution of $5%3 as a #$ of

2.3I. 9at is te concentration of te acid >

c) 9at is te #$ of A (.((11 ! solution of a%$)2>



Ans: EXAMPLE



Ans: EXAMPLE Ans: EXAMPLE



Ans: EXAMPLE



"elate te strengt of a wea+ acid and wea+ base tote res#ecti*e dissociation constant! K a and K b.

,erfor calculations in*ol*ing #$! dissociationconstant! initial concentration and te degree ofdissociation! V

WWWW alculations are liited to #robles wit quadraticequation: a2@b@cO(. A##ly a##roiationetod if &a or &b X1(-'

AD DSS%A;%5 %5S;A5; K )



Dissociation of wea+ acid in water :

/ $3%@

0 / A

0/ $A 0

K a O

ADDSS%A;%5 %5S;A5; K a)

$Aa" ) @ $2%l ) $3%@a" ) @ A a" )

KA?,L:

$5a" ) @ $2%l ) $3%@a" ) @ 5 a" )

/ $3%@ 0 / 5 0

/ $5 0

K a O



$@a" ) O $3%@a" )

KA?,L:

$5a" ) @ $2%l ) $3%@a" ) @ 5 a" )

/ $3%@ 0 / 5 0

/ $5 0K a O

or

$5a" ) $@a" ) @ 5 a" )

K a O / $@ 0 / 5 0

/ $5

0



stronger acid

iger /$3%@0

larger K a

saller K a

lower P $A dissociated

wea+er acid

or strong acids and bases dissociate 1((P):K a or K b *alues a*e not been easured



EXAMPLE

Nitrous acid, HNO2, is a weak acid that or!ed in thesto!ach when nitrite ood "reser#ati#es encounter

sto!ach acid$ %here has &een so!e concern that

this acid !a' or carcinoenic "roducts &' reaction

with "roteins$9rite te ceical equation for te equilibriuioni<ation of $5%2 in water and te a##ro#riate

K a

e#ression.



Ans: EXAMPLE

BAS DSS%A;%5 %5S;A5; K )



Dissociation of wea+ base in water :Ba" ) @ $2%l ) B$@a" ) @ %$ a" )

/ B$@ 0 / %$ 0/ B0

K b O

BASDSS%A;%5 %5S;A5; K b)

KA?,L:

5$3a" ) @ $2%l ) 5$I@a" ) @ %$ a" )

/ 5$I@ 0 / %$ 0

/ 5$3 0K b O



9en a #roton $@) is acce#ted by a wea+base contains a 5 ato! te $@ binds to a lone#air of electrons on a 5 ato of te base

KA?,L: for te reaction wit water)

5$3a" ) @ $2%l ) 5$I@a" ) @ %$ a" )

52$Ia" ) @ $2%l ) 52$'@a" ) @ %$ a" )

$3)25$a" ) @ $2%l ) $3)25$2@

a" ) @ %$

a" )



EXAMPLE

H'dra*ine is a weak &ase$ +t is a "oisonous su&stancethats so!eti!es or!ed when ch-orine &-each is

added to an a.ueous so-ution o a!!onia$

9rite te equation for te reaction of ydra<ine

52$I) wit water and write te e#ression for its K b.



Ans: EXAMPLE

#$ alculation for 9ea+ Acid




/onsider a general wea+ acid! $A$

%he ionisation equation in water is i#en &':

HA(a.) 0 H2O(-) H

O0(a.) 0 A(a.)

i*en! c O initial concentration

O concentration of $3%@ ion dissociated

HA(aq)

H3O+

(aq)A-

(aq)

Initial Conc. (M)

Change (M)

Equilibrium Conc.(M)

At equilibriu, ][

][][ 3

HA

AO H −+



&a

O ) )

c- )

&a for a wea+ acid in water $

Assu!in, that on-' a sall aount of aciddissociates, i$e$ &

a QQQ 1, thereore:

$A] O c ~ c ∴ K a !"

c2 O &

a.c

O √ &a

. )

O $3O+]




f te degree of dissociation! α is gi*en!

$Aaq) @ $2

%l) A-aq) @ $3%@aq)

i*en! c O initial concentration α O Degree of dissociation

HA(aq)

A-(aq)

H3O+

(aq)

Initial Conc. (M) c # #

Change (M) -cα

+cα

+cα

Equilibrium conc.(M) c - cα

c( $-α

)

cα

cα

At equilibriu, &a O A-

] $3%+]

$A ]




][

][][ 3

HA

AO H −+

&a 4

)1(

)()(

α

α α

−c

cc4

)1(

2

α

α

−

c4

5or a wea+ electrolyte, α is #er' s!a--$

%hus, on-' a s!a-- a!ount o acid dissociates,

Hence, &a QQQ 1, thereore: 1 - α ≈ 1

α = (&a & c) $&"

[H+] = c α = c (&a & c) $&"

= (&a. c) $&"

∴

&a c

α

2

#$ alculation for 9ea+ Base



/onsider a general wea+ base! B$

%he ionisation equation in water is i#en &':

Baq) @ $2%l) $B@aq) @ %$-aq)

i*en! c O initial concentration

O concentration of %$- ion dissociated

'(aq)

H'+(aq)

OH-(aq)

Initial Conc. (M) c # #

Change (M) -! +! +!Equilibrium conc.(M) c- ! ! !

At equilibriu, &b O B$+

] %$

]

B]




Assu!in, that on-' a sall aount of basedissociates, i$e$ &

b QQQ 1, thereore:

B]

O c

~ c

∴ K b

!"

c

2 O &b.c

O √ &b . c

O OH-]

&b for a wea+ base in water $

At equilibriu, &b O $B+]

%$

]

B ]

O ) ) c- )




Baq) @ $2%l) $B@

aq) @ %$-

aq)

f te degree of dissociation! α is gi*en!

i*en! c O initial concentration α O Degree of dissociation

'(aq) H'+(aq) OH-(aq)

Initial Concentration (M) c # #

Change (M) -cα +cα +cα

Equilibriumconcentration(M)

c( $-α

) cα

cα

At equilibriu, &b O $B+

] %$

]

B]

#



)1(

)()(

α

α α

−c

ccO

)1(

2

α

α

−

cO

5or a wea+ electrolyte,α

is #er' s!a--$%hus, on-' a sall a!ount o acid dissociates,

$ence! &b QQQ 1, thereore: 1 -

α

≈

1

α = (&

b & c) $&"

[H+] = c α = c (&b & c) $&"

= (&b. c) $&"

At e.ui-i&riu!, &b O $B+

]

%$

]

B ]

∴

&b c

α

2

S%L85 ,"%BL?S 58%L85



;wo general ty#es of #robles:

i*en equilibriu concentration! find K a or K b)

i*en K a or K b) and soe concentration

inforation! find te oter equilibriu concentrations

S% % S % 9A& AD U 9A& BAS 67LB"A

7se &' table =

Assu#tions:



Assu#tions:

/$3%@0 fro autoioni<ation of $2% is

negligible

A wea+ acid as a sall K a! So:

/$A0initial /$A0dissoc Z /$A0initial

/$A0initial O /$A0initial *ery sall)

A##ly ' P test to cec+ teassu#tion is justified



Approximationmethod or quadratic

method??

Apply theapproximation

method if Ka orKb ≤ 10-5



HOW?? xam le if Ka or Kb i!

1"# x 10

-5

$ then u!e

a roximation method if

%"# x 10

-&

$ u!e quadratic



HOW?? r your can check the !alue, if

less than / than you can

choose aro0i+ation +ethod. 1hefor+ula is :

2 3a or 3b 0 455

c6



B.7eak Base

80a+le 4 :

1he base-dissociation constant for a++onia, '"&(a9) is 4. 0 45-/ *.alculate the concentration of "- ion, " and dissociation at

e9uilibriu+ if the initial concentration of '"& is 5.4/ *.

Kb

; <initial

use approximationmethod because

Ka is 1.8 x 10-5

"83=

2 3a or 3b 0 455

c

2 1.8 x 10-5 x 100

5.4/2 4.5> less than /

(use aro0i+ation +ethod )

6

6



80ercise :

4. alculate the ercentage of "$ +olecules ioni?ed in

(a) a 5.45 * "$ solution the K a of "$ is @. 0 45 -A (.> )

use quadratic

because Ka of HF is

6.8 x 10 -4 greaterthan 10-5

"83=

2 3a or 3b 0 455c

2 6.8 x 10 -4 x 100

5.45

2 .%A +ore than /

(use 9uadratic)

66

EXAMPLE 1



EXAMPLE 1

9at is te #$ of a (.'

! $ solution at 2'

o

)>K a of $ O 4.1 1( I

Ans: EXAMPLE 1



Ans: EXAMPLE 1

Ans: EXAMPLE 1



Ans: EXAMPLE 1

EXAMPLE 2



EXAMPLE 2

alculate:a) ;e basedissociation constant! K b!

for te fluoride ion ) K a of $ O J.F 1( I

b) ;e aciddissociation constant! K a!

for te aoniu ion 5$I@)

K b of 5$3 O 1.F 1( '

Ans: EXAMPLE 2



Ans: EXAMPLE 2

Ans: EXAMPLE 2



Ans: EXAMPLE 2

"LA;%5S$, B;95 &a and &b



Dissociation of 5$3 in water:

5$3a" ) @ $2%l ) 5$I@a" ) @ %$ a" )

K b O/ 5$I

@ 0/ %$ 0

/ 5$30

% S a a d b

K a O/ 5$3

0 / $3%@ 0

/ 5$I@0

base onjugate acid

Dissociation of 5$I@ in water:

5$I@

a" ) @ $2%l ) 5$3a" ) @ $3%@

a" )

K a ! K b ! K w ! #K a ! #K b A5D #K 9



K a K b O K w

/ 5$I

@ 0 /%$-0

/ 5$30

2$2%l ) $3%@a" ) @ %$ a" )

/ 5$3 0 /$3%

@ 0

/ 5$I@0

#K a @ #K b O #K w

a ! b ! w ! # a ! # b # 9

5$3

a" ) @ $2

%l ) 5$I

@a" ) @ %$ a" )

5$I@a" ) @ $2%l ) 5$3a" ) @ $3%

@a" )

K b K a O

base onjugate acid

acid onjugate base

O / $3%@ 0/%$ 0

K a A5D #K a



#K a O N log K a

a # a

$ig K a low #K a

iger acidity

K b A5D #K b



#K b O N log K b

b # b

K b #K b

I.4I

F.44

G.I2

1I.F2

iger basicity

$ig K b low #K b

∴

Acid-dissociation constant K a) andb di i ti t t Kb)



;e *alue of K a or K b can be used to distinguis terelati*e acidity strengt of wea+ acid and wea+ base.

6 &a ↑ #K a ↓ ) O /$@0 ↑ ! tus #$ ↓ ore acidic)

6 &b ↑

#K b↓

) O /%$-0↑

! tus #$↑

ore basic)

∴base-dissociation constant K b)

80a+le :

Acid #K a

$3%%$ I.4I$%%$ 3.4J

Base #K b

J$'5$2 G.345$3 I.4I

"elati*e acidity!$%%$ $3%%$

"elati*e basicity!5$3 J$'5$2

EXE7/+8E 1



EXE7/+8E 1

A5S:a) 4.1 1( 11

b) 2.3 1( 11

a) Lactic acid, H/H9O2, is res"onsi&-e or the taste o sour !i-k$ At 2'o it K a O 1.I 1( I.

9at is te K b of its conjugate base! te

lactate ion! 3$'%2

>

b) Meth'-a!ine, /HNH2, rese!&-es a!!onia in

odor and &asicit'$ ts K b O I.I 1( I.

alculate te K a of its conjugate acid

EXE7/+8E 2; 4.1

EXE7/+8E 2



Pro"anoic acid (/2H9/OOH)(!ono"rotic)is an oranic acid whose sa-ts are used to

retard !o-d rowth in oods$

9at is te /$3%@0 of (.1( ! 2$'%%$ >

5ote: K a O 1.3 1(-'.

A5S:/$

3

%@0 O 1.1 1(-3 !

EXE7/+8E 2; 4.1EXE7/+8E 2

EXAMPLE 2 4.1

EXE7/+8E



EXAMPLE 2

;e a*erage #$ of noral arterial blood is 4.I(.At noral body te#erature 34o)!K w O 2.I 1( 1I. alculate /$@0 and /%$ 0 for blood

at tis te#erature.

A5S:a) /$@0 O I.( 1( F !

b) /%$

0 O J.( 1( 4

!

EXE7/+8E

EXE7/+8E ;



1. A (.2( ? solution of wea+ acid $K is G.IP dissociated.7sing tis inforation! calculate $3%

@ ! K- and $K

concentrations at equilibriu. Deterine also #$ and&a for $K acid.

1.FF 1(-2 ?! (.1F12 ?! 1.43! 1.4J 1(-3)

2. alculate te forate ion concentration and #$ of asolution tat is (.('( ? in foric acid.$$%2 : &a O 1.F 1(-I).

$%2- O G.( 1(-' ! #$ O 1.(( )

EXE7/+8E ;



#lain salt ydrolysis and write ydrolysis equationfor te salt fored fro te reaction between:

i. Strong acid and strong base

ii. Strong acid and wea+ base iii. 9ea+ acid and strong base

Define buffer solution

SAL; $MD"%LMSS



Salt ydrolysis: reaction of an anion or cation of asalt or bot) wit water.

eneral equation of neutrali<ation :

$K @ ?%$ ?K @ $2%

acid) base) salt) water)

?K salt dissociation equation:

?K ?@

@ K-

ation $ydrolysis : ?@aq) @ $2%l) ?%$aq) @ $@

aq)

Anion $ydrolysis : K-aq) @ $2%l) $Kaq) @ %$-aq)



$3%%5as) 5a@

a" ) @ $3%%

a" )

$2%

9at is te effect to te acidity of te solution>

KA?,L:

S#ecies eist:

5a@ and $3%%

$3%@ and %$ fro autoioni<ation of $2%

negligible)

Salt ydrolysis:

5a@ @ $2% 9at a##en >

$3%% @ $2% 9at a##en>

SAL; $MD"%LMSS : "%? S;"%5 AD A5DS;"%5 BAS



S;"%5 BAS

Anion fro strong acid l ! 5%3 ! Br ! l%I

)

5als) 5a@a" ) @ l a" )$2%

KA?,L: 5al solution

Salt consisting:

ation fro strong base 5a@! &@! Li@! a2@ )

5eiter 5a@ nor l ioni<e in water

?ay ro 5a%$ solution

?ay ro $l solution

SAL; $MD"%LMSS : "%? 9A& AD A5DS;"%5 BAS



S;"%5 BAS

Anion fro wea+ acid e.g: $3%% ! ! 5%2 )

KA?,L: $3%%5a solution

Salt consisting:

ation fro strong base 5a@! &@! Li@! a2@ )

$3%%5as) 5a@a" ) @ $3%% a" )$2%

$3%% a" ) @ $2%l ) $3%%$a" ) @ %$ a" )

5a@ does not ioni<e in water

?ay ro 5a%$solution

ro $3%%$

solution

;erefore! te ydrolysis salt equation:

SAL; $MD"%LMSS : "%? S;"%5 AD A5D9A& BAS



9A& BAS

Anion fro strong acid l ! 5%3 ! Br ! l%I

)

KA?,L: 5$Il solution

Salt consisting:

ation fro wea+ base e.g: 5$I@! $35$3

@ )

5$Ils) 5$I@a" ) @ l a" )

$2%

l does not ioni<e in water

ro 5$3 solution

ro $l solution

;erefore! te ydrolysis salt equation:



5als) 5a@a" ) @ l a" )$2%

Dissolution and dissociation of salts in water can be

written as:

or 5ala" ) 5a@a" ) @ l a" )

EXAMPLE



9rite te ydrolysis salt equation:

a) 5$I

b) al2

c) &5

d) Lil%I

e) $35$3@ 5%3

f) 5a%l

g) &l) 5$I5%3

i) 5a5%2

EXAMPLE

Ans: EXAMPLE



Ans: EXAMPLE

EXAMPLE 9 4.1

Ans: EXAMPLE



EXAMPLE 9 Ans: EXAMPLE

EXAMPLE 9 4.1

Ans: EXAMPLE



EXAMPLE 9 Ans: EXAMPLE

B7" S%L7;%5



$ow does blood aintain a constant#$ in contact wit countless cellular

acidbase reaction >

;e noral of #$ of blood is 4.I

Se*ere illness or deat can resultsfro sustained *ariation just a fewtents of a #$ unitfro tis

noral *alue

;ere ust be as syste in our body to aintain te #$ of blood or anyaqueous solution =

B7" S%L7;%5



is a solution wic as te ability to maintain its pH

wen a small amount of strong acid or strong baseis added to te solution.

t ust contains:

Acidic co#onent can react wit added /%$ 0

Basic co#onent

can react wit added /$3%@

0 ?ost coon buffer co#onents:

base - onjugate acid #air of wea+ base) %" acid - onjugate base #air of wea+ acid)



Buffer solution contains only eiter

wea+ acid or base.

f te syste contains strong acid or base!te syste A55%; act as a buffer solution.

B7""D 8s 75B7"D S%L7;%5



Solution of dilute $l

Solution of iture of1 ! $3%%$ and

1 ! $3%%5a

Addition of 1 ! $l Addition of 1 ! 5a%$

Addition of 1 ! $l Addition of 1 ! 5a%$

;e syste is not buffer solution due

to te large different of #$ *alue.

;e syste is buffer solution due tote sall different of #$ *alue.

EXAMPLE



9ic of te following are buffer systes>

a) & U $b) &Br U $Br c) 5a2%3 U 5a$%3

Ans: EXAMPLE



Deri*e te $enderson-$asselbalc equation. alculate te #$ of buffer solutions.

Decribe qualitati*ely ow a buffer solutioncontrols its #$

; t f b ff l ti

B7" S%L7;%5



;wo ty#es of buffer solutions :

i. Acidic buffer solution #$Q4)

ii. Basic buffer solution #$4)

A wea+ acid and its conjugate base

KA?,L:

?iture of $3%%$ U $3%%5a

?iture of 5$3 U 5$Il

Acidic co#onent $3%%$

Basic co#onent $3%%

A wea+ base and its conjugate acid

Acidic co#onent 5$I@

Basic co#onent 5$3

$%9 A B7" %5;"%L its #$:a#le: $3%%$ U $3%%5a



$3%%$$3%%-

$3%%-

$3%%-$3%%$

acid $@) base %$-)

A buffer syste contains etanoic acid!$3%%$

and etanoat ion! $3%%-

fro $3%%5a

$3%%$ aq) $3%%- aq) @ $@ aq)

$3

%%5a aq) $3

%%- aq) @ 5a@ aq)

$@

added) @ $3%%-

%$-added) @ $3%%$

$3%%$ $3%%- @ $2%

3 3

Addition of $3%@ :



Aount of $3%@ added O Aount of $3%% consued

O Aount of $3%%$ #roduced

$3%@a" ) @ $3%% a" ) $3%%$a" ) @ $2%l )

/$3%%-0 decrease and /$3%%$0 increase

As a result! tere will be only a sall cange in #$

$3%%-

$3%%-

$3%%$$3%%$

$@)

$3%%- aq) @ $@ $3%%$ aq)

Addition of %$ :



Aount of %$ added O Aount of $3%%$ consued

O Aount of $3%% #roduced

%$ a" ) @ $3%%$a" ) $3%% a" ) @ $2%l )

/$3%%-0 increase and /$3%%$0 decrease

As a result! tere will be only a sall cange in #$

$3%%-

$3%%-

$3%%$$3%%$

$%-)

$3%%$ aq) @ $%- $3%%- aq)

EXE7/+8E < 4.1

EXAMPLE 1



Sow ow 5$3 5$Il solution is abuffer solution.$int: dentify a co#onent in te solution tat neutrali<es acids and a co#onent

tat neutrali<es bases)

Ans: EXAMPLE 1



$5D"S%5$ASSLBAL$ 67A;%5



$Aa" ) @ $2%l ) A a" ) @ $3%@a" )

/ $3%@

0 O

or wea+ acid:

/A 0 / $3%@0

/$A0K a O

rearrange

* log K a N log /$3%@0 O

/A 0

/ $A0 * log

#$ O #K a @ log/wea+ acid0

/ onjugate base0

/A 0

/ $A0K a

$5D"S%5$ASSLBAL$ 67A;%5



5$3a" ) @ $2%l ) 5$I@a" ) @ %$-a" )

or wea+ base:

/5$I@0/%$-0

/5$30K b O

rearrange

* log K b N log /%$-0 O/5$I@0

/5$30 * log

#%$ O #K b @ log/wea+ base0

/ onjugate acid0

/5$I@0

/ 5$30K b/%$-0 O

EXAMPLE ;1 4.1

EXAMPLE 2



a) alculate te #$ of a solution containing(.2( ! $3%%$ and (.3( ! $3%%5a.

b) 9at would te #$ of a (.2( ! of

$3%%$ solution be if no salt were#resent>

K a of $3%%$ O 1.F 1( '.

EXAMPLE ;1 4.1

Ans: EXAMPLE 2



EXAMPLE ;1 4.1

Ans: EXAMPLE 2



EXAMPLE ;= 4.1

EXAMPLE



%o stud' the in-uence o an a-ka-ine !ediu!o a reaction, a buffer solution was #re#ared bydissol*ing (.12 ol of 5$3 and (.(G' ol of

5$Il in water. 9at is te #$ of te buffer>

K b of 5$3 O 1.F 1( '

EXAMPLE ;= 4.1

Ans: EXAMPLE



EXAMPLE ;= 4.1

Ans: EXAMPLE



80a+le :

EXE7/+8E 1



A buffer solution is #re#ared by iing I(( L of 1.'( ?

5$Il solution wit J(( L of (.1( ? 5$3.

i. alculate te #$ of a te buffer solution.ii. alculate te #$ of te buffer solution after te

addition ofa) (.1' ? 5a%$b) (.(11 ? $

Assue tat te *olue of te solution does not

cange wen $l and 5a%$ is added)K b for 5$3 O 1.F 1(-' ?

Ans: EXE7/+8E 1



Ans: EXE7/+8E 1



7.2 :

ACID-BASE

TITRATION



Describe the titration process and distinguish the

end point and equivalence point.

Sk tch and int rpr t th variation pH against titr valu for

titration b tw n :

i. strong acid- strong bas

ii. strong acid-w ak bas

iii. w ak acid-strong bas

Id ntify suitabl indicators for acid-bas titrations.

&M9%"DS



titration

end #oint

equi*alence #oint

indicators

titration cur*e

ADBAS ;;"A;%5



A solution of accurately +nown concentration

is added gradually to anoter solution of un+nown concentration until te ceical

reaction neutrali<ation) between te two solutionis co#lete.

ADBAS ;;"A;%5

Burette: t ti f l ti i id



onical flas+:oncentration of solution inside:un+nown KA?,L: $3%%$a" ))

ndicator:KA?,L:#enol#talein)

Before titrationbegin

After titrationat te end #oint)

oncentration of solution inside:+nown KA?,L: 5a%$a" ))

5DA;%"



ndicator is a substance tat is generally added to tesolution in te recei*ing *essel an wic undergoessoe sort of colour cange wen reaction is o*er.

A wea+ organic acid tat as different colortan it conjugate base

olor canges occurring o*er a s#ecific andrelati*ely narrow #$ range

#$ "A5



"ange o*er wic te indicator canges fro

te acid color to te base color

KA?,L:

,enol#talein#$ rangeF.3 [ 1(.(

?etyl orange3.1 [ I.I

?etyl red I.2 [ J.3

Soe oon AcidBase ndicators



olors and A##roiation #$ "ange ofSoe oon AcidBase ndicators



?ost indicators a*e a range of about 2 #$ units

acidic basicin

between

678AL5; and 5D,%5;



;e equi*alent #oint is te #oint at wic teaount of acid and base #resent eactlyneutrali<es one anoter. nuber of oles of %$-

ions and nuber of oles of $@ ions are equal)

;e end #oint of titration is te #oint wen teindicator canges colour.

;;"A;%5 7"8



Strong Acid Strong Base

9ea+ Acid Strong Base

Strong Acid 9ea+ Base

3 ty#es of acid-base titration :

;;"A;%5 7"8: Strong Acid and Strong Base ea#le: $l and 5a%$



#$

8olue of 5a%$added L)

iter etyl red or #enol#talein is a suitable indicator because eac canges color on te

stee# #ortion of te cur*e

,enol#talein

#$ range

F.3 [ 1(.(

?etyl red I.2 [ J.3

9A& ADS;"%5 BAS 7"8S



;ree different wit strong acidstrong base:

nitial #$ is iger

9ea+ acid dissociates sligtly

radual rising #ortion buffer region

?iture of acid and salt

$AUA buffer syste #roduced

#$ at equi*alence #oint 4.((

Salts of wea+ acid and strong base

a#le: $3%%

5a@

) is basic in water

;;"A;%5 7"8: 9ea+ Acid and Strong Base ea#le $3%%$ and 5a%$)



,enol#talein is a suitable indicator because itcanges color on te stee# #ortion of te cur*e! butetyl red is not its color canges o*er a large

*olue range

,enol#talein

#$ range

F.3 [ 1(.(

?etyl red I.2 [ J.3#$

S;"%5 AD9A& BAS 7"8S



KA?,L: 5$3a" ) in conical flas+

$la" ) in burette

nitial solution O wea+ base #$ 4.((

radual rising #ortion buffer region ?iture of base 5$3) and salt 5$I

@)

#$ at equi*alence #oint Q 4.((

Salt 5$I@l ) is acidic in water

#$ decrease slowly as ecess $3%@ is

added

;;"A;%5 7"8: Strong Acid and 9ea+ Base ea#le: $l and 5$3 )



?etyl red is a suitable indicator because it cangescolor on te stee# #ortion of te cur*e! but#enol#atalein is not its color canges o*er a large

*olue range

,enol#talein

#$ range

F.3 [ 1(.(

?etyl red I.2 [ J.3

#$

EXAMPLE



S+etc titration cur*es for te following

acidbase titrations:

a) $l *ersus 5a%$b) $l *ersus $35$2

c) $3%%$ *ersus 5a%$

n eac case! te base is added to te acidin a conical flas+. Mour gra# sould sow

#$ on te yais and *olue of base addedon te ais.

Ans: EXAMPLE



#$

8olue of

5a%$ added

4.(( equi*alence#oint

a) ;itration cur*e: $l *ersus 5a%$

Ans: EXAMPLE



#$

8olue of

5a%$ added

Q 4.((

buffer region

b) ;itration cur*e: $l *ersus $35$2

equi*alence#oint

Ans: EXAMPLE



#$

8olue of

5a%$ added

4.(( equi*alence#oint

;itration cur*e: $3%%$ *ersus 5a%$

buffer region

EXE7/+8E 4.1

EXE7/+8E 1



ndicator " range colour change

henolhthalein .% C 45.5

*ethyl orange &.% C .%

Bro+othy+olblue

@.5 C .@

henol red @. C .

1. 9at is te colour of te solution wen 3 dro#s of tebelow indicators are added se#arately to water #$ O 4) >



Define solubility! olar solubility and solubility#roduct! K s#.

alculate K s# fro concentration of ion and *ice

*ersa ,redict te #ossibility of #reci#itation of sligtly

soluble ionic co#ounds te *alues of ion-#roduct!Q to K s#.

Define and e#lain te coon ion effect. ,erfor calculations related to coon ion effect.

&M9%"DS



solubility

olar solubility

solubility #roduct K s#)

Q

#reci#itation

coon ion effect

Solubility and ?olar Solubility

Solubility: is te aiu aount of solute g or ole



Solubility: is te aiu aount of solute g or oleor +g) tat can be dissol*ed in a gi*en quantity of

sol*ent to for a saturated solution at a gi*ente#erature. or ea#leT

Solubility gUL)

ras of solute dissol*ed in 1 L of a saturated

solution ?olar solubility olUL):

?oles of solute dissol*ed in 1 L of a saturatedsolution

8uar (so-ute)

+n !a> a!ount

A cu" ?itter tea

(so-#ent)

@er' sweet tea

(saturated so-ution)

@

S%L7BL;M % SL$;LMS%L7BL %5 %?,%75DS



,bl2s)

Assu#tion: ;e sall aount of a sligtly

soluble ionic co#ound tat dissol*es in water also dissociates co#letely into ions

Sligtly soluble ,bl2a" )

1((P dissociates into ions

,b2@

a" ) 2l

a" )

,bl2s) ,b2@a" ) @ 2l a" )

KA?,L:

quilibriu eist between solid solute andaqueous ions:



,bl2s) ,b2@a" ) @ 2l a" )

KA?,L:

Ag2Ss) 2Ag@a" ) @ S2a" )

KA?,L: Saturated solution of Agl in water

S%L7BL;M,"%D7; %5S;A5;! K s#



KA?,L: Saturated solution of Agl in water

Agls) Ag@a" ) @ l a" )

K s# O /Ag@0 /l 0

An equilibriu constant related to te

equilibriu between solid salt and its ions in solution

ts #ro*ide a quantitati*e easure of te

solubility of a sligtly soluble salt

&s# : ;e #roduct of ion concentrations in saturated

solution! eac raised to te #ower of itsstoicioetric in te equilibriu equation.

S l bl i i d 1(( P l bl d di i t



Soluble ionic co#ounds 1(( P soluble and dissociatein water) suc as 5al a*e no K s# *alue



Ans: EXAMPLE



7S5 K s# ;% %?,A" S%L7BL;S



?g%3s) ?g2@a" ) @ %32a" )

K s# \ Solubility \

KA?,L:

K sp O 3.' 1( F

,bS%Is) ,b2@a" ) @ S%I2a" ) K sp O 1.J 1( F

?g%3

is ore soluble tan ,bS%I

Mou ust co#are K s# of co#ounds

wose forula a*e sae total nuber of ions

AL7LA;%5 58%L85 K s#



Deterining K s# fro

solubility or olar solubility

Deterining solubility orolar solubility fro K s#

;wo ty#es:

EXAMPLE 1



A5S:'.( 1( 13

8i-#er &ro!ide, A?r, is the -ihtsensiti#e

co!"ound used in near-' a-- "hotora"hic i-!$ ;e olar solubility of AgBr is 4.1 1( 4 ! .at 2'o. alculate K s# for AgBr at tis

te#erature.

Ans: EXAMPLE 1



EXAMPLE 2



A5S:1.3 1( I

;e solubility of sil*er carbonate is

(.(32 ol L 1 at 2(o. alculate te K s# of sil*er carbonate.

Ans: EXAMPLE 2



EXAMPLE



;e solubility of calciu sulfate is founde#erientally to be (.J4 gUL.alculate te *alue of K s# for calciu sulfate.

?olar ass of aS%I O 13J.2 gUol)

A5S:

2 I 1( '

Ans: EXAMPLE



Ans: EXAMPLE



9en &s# is gi*en!



EXAMPLE 1



A5S:1.3 1( ' ol L 1

9at is te olar solubility of Agl in

#ure water at 2'o>K s# of Agl O 1.F 1( 1(

Ans: EXAMPLE 1



alculate te olar solubility of ,bl

EXAMPLE 2



alculate te olar solubility of ,bl2.

K s# O 1.J 1( '

A5S:

1 J 1( 2

!

Ans: EXAMPLE 2



EXE7/+8E 4.1

EXE7/+8E 1



1. ;e solubility of agnesiu ydroide! ?g%$)2 is

1.4 1(-I ol d-3. alculate te solubility #roduct oftis co#ound.

2. ;e solubility of calciu sulfate! aS%I is founde#erientally to be (.J4 g L-1. alculate te K s# *alue

for aS%I. ?olar ass of aS%I O 13J.2 g ol-1)

3. 1.(( liter of a saturated solution of sil*er croate!Ag2r%I at 2'o contains (.(I3' gra of dissol*ed

Ag2r%I. alculate its olar solubility and its solubility

roduct constant

6 O K s#

+rediction o precipitation, Q s# 8s. K s#



s#

- te solution is saturated

- equilibriu eist between undisol*esolid salt and its dissol*ed ions

6 Q K s#

- te solution is unsaturated- no #reci#itation of ?A- ore salt sould be dissol*ed to increase

te ion concentrations until 6 O K s#

6 K s#

- te solution is su#ersaturated- ?As) will #reci#itate out until te #roduct

of te ionic concentrations is equal to Ks#

?ore solid candissol*e =

EXAMPLE 1



A5S:,reci#itate will for until Q

s#

O K s#

9ill a #reci#itate of aS%I for in a solution

if te a2@ concentration is (.((2' ! and teS%I

2 concentration is (.(3( ! >

K s# of aS%I O 2.I 1( ')

Ans: EXAMPLE 1



9 ibl i i i f b

EXAMPLE 2



9at #ossible #reci#itate igt for by

iing '(.( L of 1.( 1( I ! 5al wit'(.( L of 1.( 1( J ! Ag5%3> 9ill it for>

K s# of Agl O 1.F 1( 1()

A5S:Q s# O 2.' 1( 11

Agl #reci#itate will not for

Ans: EXAMPLE 2



Ans: EXAMPLE 2



%??%5 %5 ;

Sift of equilibriu caused by addition or te



Sift of equilibriu caused by addition or te

te #resence of a co#ound a*ing an ion incoon wit te dissol*ed substance

,br%Is) ,b2@a" ) @ r%I2a" )

Add r%I2

KA?,L:

,resence of a coon ion decreases solubility

; % %??%5 %5%5 S%L7BL;M



,resence of a coon ion decreases solubility

of sligtly soluble ionic co#oundKA?,L: Addition of 5a2r%I soluble salt) to

saturated solution of ,br%I

,br%Is) ,b2@a" ) @ r%I2a" )

K s# O /,b2@0/r%I20 O 2.3 1(-13

Add r%I2-

ffect of te addition of coon ion r%I2 :

/r%I20 \ Soe r%I

2 cobine wit

,b2@ to for solid ,br%I

Solubility of ,br%I ]

,b2@

,br%I

Add r%I2



,b

r%I2

,br%I

,b2@

r%I2

,br%I

,br%I dissol*es in 5a2r%I solution

;e sae results if:

Soluble lead )salt suc as ,b5%3)2 is added

9at is te olar solubility of AgBr in

EXAMPLE 1



9at is te olar solubility of AgBr in

a) #ure waterb) (.((1( ! 5aBr >.

K s# of AgBr O 4.4 1( 13

A5S:a) F.F 1( 4 !

b) 4.4 1( 1( !

Ans: EXAMPLE 1



Ans: EXAMPLE 1



l l t t l bilit f il l id

EXAMPLE 2



A5S:a) 1.F 1( 3 gULb) 3.J 1( J gUL

alculate te solubility of sil*er cloride

in gUL) in

a) #ure water b) a J.' 1( 3 ! sil*er nitrate solution

K s# of Agl O 1.J 1( 1(

Ans: EXAMPLE 2



Ans: EXAMPLE 2



1 t f d i t ll t t t l bilit f

EXAMPLE

EXE7/+8E 4.1

EXE7/+8E 1



1. t was found e#erientally tat te solubility of

calciu sul#ate is (.J4 g L-1. alculate te K s# forcalciu sul#ate. 2.I 1(-I )

2. ;e solubility of sil*er sul#ate is 1.' 1(-2 ol L-1.alculate te solubility #roduct of te salt. 1.I 1(-' )

3. 9ill #reci#itate for if 2(( L of (.((I( ? Bal2 areadded to J(( L of (.((F( ? &2S%I > K s# BaS%I O 1.1

1(-1() 6 K s# terefore BaS%I will #reci#itate)



&idney Stone



Are #ains sooting troug your body tat are so se*ere tat tey cause you to curl u# in #ain>

Does your lower bac+ feel li+e being stabbed o*er and o*er again wit

a ot +nife>

Are your #ains so se*ere tat a+e you feel nauseous or e*en cause

you to *oit>



a2@a" ) @ 2%I2a" ) a2%Is)

;e noral #ysiological concentration of calciu ions in blood #lasa is about ' !

%alate ion 2%I2)! deri*ed fro oalic acid #resent

in any *egetables suc as rubarb and s#inac! reac wit calciu ions to for insoluble calciu oalate! wic can gradually build u# in te +idneys

7.0 Ionic Equilibria (Students)

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Transcript of 7.0 Ionic Equilibria (Students)