Chapter 19 Powerpoint l (1)

8/17/2019 Chapter 19 Powerpoint l (1)

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19-1

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Chapter 19

Ionic Equilibria in Aqueous Systems


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19-#


Ionic Equilibria in Aqueous SystemsIonic Equilibria in Aqueous Systems

19.1 Equilibria of Acid-Base Buffer Systems

19.2 Acid-Base itration Cur!es

19." Equilibria of Sli#htly Soluble Ionic Compounds

19.$ Equilibria In!ol!in# Comple% Ions


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19-$


Figure 19.1

he effect of addition of acid or base to &

an unbuffered solution

or a buffered solution

aci! a!!e! %ase a!!e!

aci! a!!e! %ase a!!e!

Figure 19.2


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19-&


able 19.1

The '""ect o" (!!e! (cetate Ion on the )issociation o" (cetic (ci!

'C("C))(*initial 'C("C))-*added + ,issociation p(

* + )issociation CH$CH/!issoc

CH$CH/initial

0 1

.1 .

.1 .2

.1

.1 .1

.12

1.$

.$3

.14

.1#

#.49

&.&&

&.5&

&.9#


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19-2


Figure 19.3 (o a buffer or/s.

6""er with eqalconcentrations o"

con7gate %ase an! aci!

H-

H$8

6""er a"ter a!!ition o" H$

8

H# 8 CH$CH H$8 8 CH$C

-

6""er a"ter a!!ition o" H

-

CH$CH 8 H- H# 8 CH$C

-


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19-3


Sample 0roblem 19.1 Calculatin# the Effect of Added (") or )(-

on Buffer p(

0)B3E45 Calclate the pH

6a7 o" a %""er soltion consisting o" .2M CH$CH an! .2M CH$C:a

6b7 a"ter a!!ing .#mol o" soli! :aH to 1.; o" the %""er soltion in part


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Sample 0roblem 19.1 Calculatin# the Effect of Added (") and )(-

on Buffer p(

continued 62 of $7

CH$CH/eqil B .2M CH$C-/initial B .2MH$

8/ x

>a H$

8/CH$C-/

CH$CH/H$

8/ x >aCH$C

-/

CH$CH/ 1.401-2M

ChecA the assmption 1.401-2.2 D 1 $.301-$ +

C("C))(6 aq7 )(-

6 aq7 C("C))-

6 aq7 (2)

6l 7Concentration 647

6e"ore a!!ition

(!!ition

("ter a!!ition

6b7H-/a!!e!

.# mol

1.; soln .#M :aH

.2 - .2 -

-

-

- .# -

.&4 .2#


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on Buffer p(

continued 6" of $7

Eet p a reaction table with the new ?ales.

C("C))(6 aq7 (2)6l 7 C("C))-6 aq7 (")

6 aq7Concentration 647

Initial

Change

'qili%rim

.&4 -

- x

.&4 - x

-

-

.2#

x

8 x 8 x

.2# 8 x

H$8/ 1.401-2

.&4

.2# 1.501-2 pH &.55

C("C))-6 aq7 (")

6 aq7 C("C))(6 aq7 (2) 6l 7Concentration 647

6e"ore a!!ition

(!!ition

("ter a!!ition

6c7 H$8/a!!e!

.# mol

1.; soln .#M H$

8

.2 - .2 -

-

-

- .# -

.&4 .2#


9/3819-9



on Buffer p(

continued 6$ of $7

Eet p a reaction table with the new ?ales.

C("C))(6 aq7 (2)6l 7 C("C))-6 aq7 (")

6 aq7Concentration 647

Initial

Change

'qili%rim

.2# -

- x

.2# - x

-

-

.&4

x

8 x 8 x

.&4 8 x

H$8/ 1.401-2

.&4

.2# #.01-2 pH &.5


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he (enderson-(asselbalch Equation

(A (2) (") A-

:a ; '(")* 'A-*

'(A*

'(")* ; :a '(A*

'A-*

- lo#'(")* ; - lo# :a lo#

'A-*

'(A*

p( ; p:a lo#'base*

'acid*


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Buffer Capacity and Buffer an#e

Buffer capacity is the ability to resist p( chan#e.

Buffer ran#e is the p( ran#e o!er hich the buffer acts effecti!ely.

The more concentrate! the components o" a %""er, the greater

the %""er capacity.

The pH o" a %""er is !istinct "rom its %""er capacity.

( %""er has the highest capacity when the component

concentrations are eqal.

6""ers ha?e a sa%le range within F 1 pH nit o" the p>a o"

its aci! component.

C © G C "


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Figure 19.4 he relation beteen buffer capacity and p( chan#e.

C i ht ©Th M G Hill C i I P i i i ! " ! ti !i l


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0reparin# a Buffer

1. Choose the con7gate aci!-%ase pair.

#. Calclate the ratio o" %""er component concentrations.

$. )etermine the %""er concentration.

&. Mi0 the soltion an! a!7st the pH.

C i ht ©Th M G Hill C i I P i i i ! " ! ti !i l


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Sample 0roblem 19.2 0reparin# a Buffer

S)3I)85

0)B3E45 (n en?ironmental chemist nee!s a car%onate %""er o" pH 1.

to st!y the e""ects o" the aci! rain on limsetone-rich soils. Howmany grams o" :a#C$ mst she a!! to 1.2; o" "reshly prepare!

.#M :aHC$ to maAe the %""er >a o" HC$- is &.501-11.

03A85 @e Anow the >a an! the con7gate aci!-%ase pair. Con?ert pH to

H$8/, "in! the nm%er o" moles o" car%onate an! con?ert to mass.

(C)"-6 aq7 (2)6l 7 C)"

2-6 aq7 (")6 aq7 >a

C$#-/H$

8/

HC$-/

pH 1. H$

8/ 1.01-1 &.501-11 C$

#-/


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pH

Figure 19.5Colors and appro%imate p( ran#e of some

common acid-base indicators.

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16/3819-13


Figure 19.6 he color chan#e of the indicator bromthymol blue.

aci!ic

%asic

change occrs

o?er #pH nits

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17/3819-15


Figure 19.7 Cur!e for a stron# acid-stron# base

titration.

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18/3819-14


Figure 19.8

Cur!e for a

ea/ acid-stron# base

titration.

itration of $


19/3819-19

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Sample 0roblem 19." Calculatin# the p( ,urin# a =ea/ Acid-

Stron# Base itration

0)B3E45 Calclate the pH !ring the titration o" &. m; o" .1M

propanoic aci! a 1.$01-2= a"ter a!!ing the "ollowing

?olmes o" .1M :aH6a7 .m; 6b7 $.m; 6c7 &.m; 6d7 2.m;

03A85 The amonts o" HPr an! Pr - will %e changing !ring the titration.

Jemem%er to a!7st the total ?olme o" soltion a"ter each a!!ition.

S)3I)85 6a7 Kin! the starting pH sing the metho!s o" Chapter 14.

>a Pr -/H$

8/HPr/ Pr -/ x H$8/ Pr -/ x H$

8/

x = (1.3 x 10−5)(0.10) x 1.101

-$ pH #.93

6b76e"ore a!!ition

(!!ition

("ter a!!ition

.&

.$

.$.1

-

-

-

-

- -

(0r6 aq7 )(-

6 aq7 0r -

6 aq7 (2)

6l 7Amount 6mol7

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20/38

19-#


Sample 0roblem 19." Calculatin# the p( ,urin# a =ea/ Acid-

Stron# Base itration

continued

H$8/ 1.$01-2

.1 mol

.$ mol &.$01-3M pH 2.$5

6c7 @hen &.m; o" :aH are a!!e!, all o" the HPr will %e reacte! an! the Pr -/

will %e w >% >w>a 1.01-1&1.$01-2 5.501-1

H$8/ >w 1.301

-9M K bx[Pr

−] pH 4.4

6d7 2.m; o" :aH will pro!ce an e0cess o" H-.

mol DE %ase


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19-#1


Figure 19.9

Cur!e for a

ea/ base-

stron# acid

titration.

itration of $


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19-##

py g p , q p p y

Ion-0roduct E%pression 6>sp7

and Solubility 0roduct Constant 6:sp7

At equilibrium >sp ; '4n*p '?@-*q ; :sp

or the hypothetical compound 4p?q



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19-#$

py g p , q p p y

Sample 0roblem 19.$ =ritin# Ion-0roduct E%pressions for Sli#htly

Soluble Ionic Compounds

S)3I)85

0)B3E45 @rite the ion-pro!ct e0pression "or each o" the "ollowing

6a7 Magnesim car%onate 6b7 Iron


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19-#&

py g p q p p y

able 19.2 Solubility-0roduct Constants 6:sp7 of Selected Ionic

Compounds at 2


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19-#2

Sample 0roblem 19. ,eterminin# :sp from Solubility

0)B3E45 6a7 ;ea! sp o" P%K#.

03A85 @rite the !issoltion eqation "in! moles o" !issociate! ionscon?ert sol%ility to M an! s%stitte ?ales into sol%ility pro!ct

constant e0pression.

>sp P%#8/E&

#-/

1.&01-&M P%E&

>sp P%#8/E&

#-/


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19-#3

Sample 0roblem 19. ,eterminin# :sp from Solubility

continued

6b7 P%K#


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19-#5

Sample 0roblem 19.D ,eterminin# Solubility from :sp

0)B3E45 Calcim hy!ro0i!e sp is 3.201-3.

03A85 @rite ot a !issociation eqation an! >sp e0pression Kin! the molar

sol%ility


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19-#4

able 19." Jelationship 6etween >sp an! Eol%ility at #2C

8o. of Ions ormula Cation5Anion :sp Solubility 647

# MgC$ 11 $.2 0 1-4 1.9 0 1-&

# P%E& 11 1.3 0 1-4 1.$ 0 1-&

# 6aCr& 11 #.1 0 1-1 1.& 0 1-2

$ Ca


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19-#9

Figure 19.10 he effect of a common ion on solubility.

P%Cr&


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19-$

Sample 0roblem 19. Calculatin# the Effect of a Common Ion on

Solubility

0)B3E45 In Eample Pro%lem 19.3, we calclate! the sol%ility o" Ca


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19-$1

Figure 19.11 est for the presence of a carbonate.



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19-$#

Sample 0roblem 19.F 0redictin# the Effect on Solubility of Addin#

Stron# Acid

0)B3E45 @rite %alance! eqations to e0plain whether a!!ition o" H$8 "rom a

strong aci! a""ects the sol%ility o" these ionic compon!s

6a7 ;ea!


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19-$$

Sample 0roblem 19.9 0redictin# =hether a 0recipitate =ill orm

0)B3E45 ( common la%oratory metho! "or preparing a precipitate is to mi0

soltions o" the component ions. )oes a precipitate "orm when

.1; o" .$M Casp ?als in a ta%le. Treat this as a reaction qotient, N,

pro%lem an! calclate whether the concentrations o" ions are O or

>sp. Jemem%er to consi!er the "inal !ilte! soltion when calclating

concentrations.

S)3I)85 CaK#


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19-$&

Figure 19.12 ormation of acidic precipitation.



35/38

19-$2

Figure 19.13 Cr68("7D" a typical comple% ion.



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19-$3

Figure 19.14

46(2)7$2

46(2)7"68("72

468("7$2

8("

"8("

he stepise e%chan#e of 8(" for (2) in 46(2)7$2.



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19-$5

Sample 0roblem 19.1< Calculatin# the Effect of Comple%-Ion ormation

on Solubility

S)3I)85

0)B3E45 In %lacA-an!-white "ilm !e?eloping, e0cess (g6r is remo?e! "rom

the "ilm negati?e %y hypoQ, an aqeos soltion o" so!im

thiosl"ate sp to "in! E, the molar

sol%ility. Consi!er the shi"ts in eqili%ria pon the a!!ition o" thecomple0ing agent.

(g6r


38/38

Sample 0roblem 19.1< Calculatin# the Effect of Comple%-Ion ormation

on Solubilitycontinued

>o?erall >sp 0 >" 6r -/(g

Chapter 19 Powerpoint l (1)

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