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ECHILIBRE

-

1

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DISOCIEREA APEIDISOCIEREA APEI2 H2 H22OO HH33OO

++ + OH+ OH-- HH33OO++ HH++

PRODUS IONIC AL APEI:+ 214 o

OHc 2==

2OH =

N APA PUR POHH OH710][][

2

+ ===

H 10][ + > NTR-O SOLUIE ACID

2MH

7

10][

+

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+=

RELAIA DINTRE pH I pOH:

4

=+ pp

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LOGARITMUL

xbxb =log

b baza b > 0 b 1

x argumentul x > 0

xbyxy

b ==log

LOGARITMI UZUALI

10

5

log ln logaritm naturalex x=

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PROPRIETI:

1 lo 1b=

p

=

b b

4) log log logb b bx yy

=

6

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SCARA H SSCARA H Srensenrensen

HH

10 10 . . . . 10. . . . 10--

. . . . 10. . . . 10--

pH 0 . . . . 7 . . . . 14pH 0 . . . . 7 . . . . 14 . . . . . . . .. . . . . . . .

NEUTRU

7ACID BAZIC

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lg10][][ 14 = + OHH

1410lg][lg][lg + = OHH

14pOHpH

Exprimarea [H+] ntr-o soluie cu pH cunoscut

][lg += HpH pHH =+ ][lg

8pHH + = 10][

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HH22SOSO44, HNO, HNO33 (1300)(1300)

TEORIA ARRHENIUS (1890)TEORIA ARRHENIUS (1890)

Acidul este o substancare produceAcidul este o substancare produce

Baza este o substancare produceBaza este o substancare produceioni hidroxil cnd este dizolvatn apioni hidroxil cnd este dizolvatn ap

TEORIA BRNSTEDTEORIA BRNSTED LOWRY (1923)LOWRY (1923)Acid = substancapabilscedeze protoni (HCl)Acid = substancapabilscedeze protoni (HCl)

9Baz= substancapabilsaccepte protoni (NHBaz= substancapabilsaccepte protoni (NH33))

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ACIZI SLABI +

PP FORMPROTONATFORMPROTONAT

cc az con ugaaz con uga

HH22OO OHOH

DD FORMDEPROTONATFORMDEPROTONAT22 33 33

NHNH44++ NHNH33

10

CHCH33COOHCOOH CHCH33COOCOO

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pHpH UL SOLUUL SOLUIILOR DE ACIZI TARIIILOR DE ACIZI TARI

AHAH AA

+ H+ H ++

Iniial: c 0 0Final: 0 c c

cHpH lg][lg == +

EXEMPLE: HClO4, H2SO4, HI, HBr, HCl, HNO3

11

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12

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EXEMPLU

pH ?= [ ] 10 MHCl

=3pH lg lg10 3c = = =

TEM*

= 7=

13

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pHpH UL SOLUUL SOLUIILOR DE BAZE TARIIILOR DE BAZE TARI

BOHBOH BB++ + OH+ OH

Iniial: c 0 0

Final: 0 c c

cOHpOH lg][lg ==

14

, , 2, 2

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15

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PROBLEM 100 mLV=

p = 1 1mg am = =

2 2, ,

340 10m 1 3

1 40 100 10c

M V

= = =

3

222 3

2

,10 M

58,5 100 10c

M V

= = =

1pOH lg lg10 2c = = =

16

pH 14 2 12= =

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SOLUSOLUIIII DE ACIZI SLABIDE ACIZI SLABI

HAHA AA-- + H+ H ++

Iniial: c 0 0

Final: c x x x

xAH + 2

xcHAKHA

== ][

MASELOR

17

x c c x c

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18

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SubstanaSubstana FormulaFormula KKaa pKpKaa-- 33 , , ,,

AcidAcidcarboniccarbonic

HH22COCO33 4,3 104,3 10--77

4,8 104,8 10--11116,16,110,210,2

Acid fosforicAcid fosforic HH33POPO44 6,9 106,9 10--336,2 106,2 10--88 2,12,17,27,2 KpK lg=, , -- ,,

ACIZI POLIBAZICIACIZI POLIBAZICI

16=+ + KHHCOCOHTREAPTA ITREAPTA I

2,102233 =+ +

pKHCOHCOTREAPTA IITREAPTA II

19

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pHpH UL SOLUUL SOLUIILOR DE ACIZI SLABIIILOR DE ACIZI SLABI

A. Se cunosc [HA] i pK

+ 2

[H ] p lg[HA]pH[HA] 2KK = =

B. Se cunosc [HA], [A ] i pK+ -[H ] [A ] [ ]

pH p lgD

K K

= = +

20

--

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SISTEME TAMPONSISTEME TAMPON

DEFINIDEFINIIEIE

AMESTECURI DE SUBSTANAMESTECURI DE SUBSTANE CAREE CARE MENMENININCONSTANT pHCONSTANT pH UL SOLUUL SOLUIEIIEI

COMPOZICOMPOZIIE:IE:

ACID SLAB (A) + SAREA SA (S)ACID SLAB (A) + SAREA SA (S)

DISOCIERE: ADISOCIERE: A PARPAR IAL SIAL S TOTALTOTAL

22

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CALCULUL pHCALCULUL pH ULUI:ULUI:

][lg

DpKpH +=

FORMULA HENDERSONFORMULA HENDERSON

V=

pH

SISTEME TAMPON ALE SSISTEME TAMPON ALE SNGELUI:NGELUI:

22 33 33 HH22POPO44

+ HPO+ HPO44

22

23 Hb acidHb acid + hemoglobinat de K+ hemoglobinat de K

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3,123=pK

2,72 =pK

,1

24

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FORMA IONICFORMA IONIC PREDOMINANTPREDOMINANT

-

CE FORMIONICARE CONCENTRAIE

][l DKH +=

][P

][][ PDpKpH ==DAC

27

][][ PDpKpH >>

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EXEMPLUEXEMPLU

CHCH33COOHCOOH HH++ + CH+ CH33COOCOO

pKa

CHCH33COOHCOOH CHCH33COOCOO

PentruPentru pH < pK pH < pKaa predominpredomin CHCH33COOHCOOH

28

PentruPentru pH > pK pH > pKaa predominpredomin CHCH33COOCOO

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,1 ,2 ,3

29

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pHpH--UL IZOELECTRIC AL PROTEINELORUL IZOELECTRIC AL PROTEINELOR

CARACTER AMFOTER:

GRUPRI CARBOXIL (- COOH)COOH COO H +

++ + 2

DEFINI IE I SAU H :

2 3

SEMNUL SARCINII ELECTRICEZ:

pH < pI Z> 0

31

pH > pI Z< 0

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Z= 0Z> 0 Z< 0

pH

(NH3+

)a (NH2)a

p

R R

32

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pHpH -- UL UNOR MEDII BIOLOGICEUL UNOR MEDII BIOLOGICE

SSNGE:NGE: 7,387,38 7,437,43

MEDIU INTRACELULARMEDIU INTRACELULAR:: 6,96,9 7,07,0

SUC GASTRICSUC GASTRIC:: 11 22

SALIV :SALIV : 7,17,1 7,47,4

SUC PANCREATICSUC PANCREATIC:: 88 99

URINURIN:: 5,85,8 6,26,2

UMOARE APOAS, LIMFUMOARE APOAS, LIMF:: 7,97,9

33 ACIZI BILIARI:ACIZI BILIARI: 3,83,8 4,34,3

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34

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CAPACITATEA DE TAMPONARE A SALIVEICAPACITATEA DE TAMPONARE A SALIVEI

SISTEME TAMPON SALIVARESISTEME TAMPON SALIVARE HH22COCO33 + HCO+ HCO33

HH22POPO44

+ HPO+ HPO4422

TESTUL ERICSSON: 1TESTUL ERICSSON: 1 mLmL salivsaliv + 3 ml+ 3 ml soluiesoluie HClHCl 55 mMmM,,

barbotatbarbotat cu Ncu N22 timptimp de 20 min. pt.de 20 min. pt. eliminareaeliminarea COCO22..pH FINAL CAPACITATE DE TAMPONARE

pH > 5.5 RIDICAT

. .

pH < 4.5 REDUS

TESTE CANTITATIVE (pHTESTE CANTITATIVE (pH metriemetrie electronicelectronic))

35 TESTE CALITATIVE (TESTE CALITATIVE (colorimetriecolorimetrie))

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PELICULA SALIVARN MEDIU ACIDPELICULA SALIVARN MEDIU ACID1 min. n pH 2.36Pelicula

(acid citric 1%)orman

12 h

6 h

2 h

36Hanni et al. 2003 Clin. Oral Invest. 7:158-161.

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DEMINERALIZAREA SMALULUIDEMINERALIZAREA SMALULUII CARIILE DENTAREI CARIILE DENTARE

REAC IA DE DEMINERALIZAREREAC IA DE DEMINERALIZARE

+ 2+ 2-10 4 6 2 4 2Ca (PO ) (OH) (s)+8H (aq) 10Ca (aq)+6HPO (aq)+2H O(l)

37Hidroxiapatita

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DEMINERALIZAREA SMALULUIDEMINERALIZAREA SMALULUI< 5 zile n

pH 4.5dinte

primar

permanent

38Wan et al. 2006 J Dent Res 85:359-363.

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DEMINERALIZAREA SMALULUIDEMINERALIZAREA SMALULUI

biofilm S. mutans

Biofilm S.

mutans

Profilometrieoptic

de fortatomic

39Cross et al. 2009 Dental Materials 25:1517-1526.

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FORMAREAFORMAREA

DENTAREDENTARE

StreptococcusStreptococcus MutansMutans

Kidd EAM Jo ston-Bechal S.

Essentials of dental caries:The disease and its

management. 2nd ed.

40

New York: Oxford University

Press, 1997.

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THE ENDTHE END

41