Acids, Bases and Buffers New

7/26/2019 Acids, Bases and Buffers New

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ACIDS, BASES AND BUFFERS

Dr. Bintang Simbolon, MSi17/12/15


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GOALS

Larning !b"#ti$% &

Larn abo't t( rlation bt)n *+ an a#i %ol'tion

Larn abo't t( rlation bt)n *- an a#ii%%o#iation

Unr%tan t( nition an 'n#tion o b'0r

Unr%tan t(at a#i *rotin i% a0#t b b'0r

Unr%tan t(at *I $al' #a'%% n'tral *rotin

Larning !'t#om

Unr%tan t( *rotin in t( bo 'i or 3am*l +b#an 'n#tion a% b'0r


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Intro'#tion

Man #om*o'n% in t( bo #ontain #(mi#al gro'*%t(at #an a#t a% a#i% or ba%%, rla%ing or a##*ting*roton%. 4(ror, t( ma #arr a #(arg at*(%iologi#al *+. 4(% #om*'n% rang rom t( %mall

mol#'l% %'#( a% A4 to larg *olmr% %'#( a% t(*rotin (moglobin.

Mo%t bio#(mi#al ra#tion% o##'r in a6'o'% %ol'tion.atr i%%o#iat% to a %lig(t 3tnt to orm +8an !+9.

4( #on#tration o (rogn ion%, :+8;, trmin% t(a#iit o t( %ol'tion, )(i#( i% '%'all 3*r%% intrm% o *+. 4( *+ o a %ol'tion i% t( ngati$ log oit% (rogn ion #on#ntration


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An a#i i% a %'b%tan# t(at #an rla% (rognion% , )(ra% a ba% i% a %'b%tan# t(at#an a##*t (rogn ion%. In %ol'tion, almo%t allt( mol#'l% o a %trong a#i i%%o#iat, b't onl

a %mall n'mbr o t( total mol#'l% o a )a?a#i i%%o#iat. A )a? a#i (a% a #(ara#tri%ti#i%%o#iation #on%tant, -a.

4( rlation%(i* bt)n *+, *-a, an t(#on#ntration% o a )a? a#i an it% #on"'gatba% i% %#rib b t( +nr%on9+a%%lbal#(6'ation


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A b'0r i% a mi3t'r o an 'ni%%o#iat a#ian it% #on"'gat ba% t(at #a'%% a %ol'tionto r%i%t #(ang% in *+ )(n it(r +8or !+9

ar a. A b'0r (a% it% grat%t b'0ring#a*a#it in t( *+ rang nar it% *-a.

B#a'% a#i% ar *ro'# in t( #o'r% o

normal mtaboli%m, t( bo m'%t (a$b'0r% t(at #an maintain t( *+ in a rang#om*atibl )it( li.


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atr

atr i% t( %ol$nt o li. Abo't t)o t(ir% o o'r bo)ig(t i% )atr. it( t( 3#*tion o ra#tion% t(at o##'rin li*i mmbran%, t( ra#tion% o t( bo o##'r in ana6'o'% mi'm. B#a'% )atr mol#'l% ar *olar, t(#an intra#t )it( a#( ot(r. Ea#( o t( 2 (rogn atom%in a )atr mol#'l %(ar% it% l#tron% )it( t( 'n%(arl#tron% o t( o3gn atom.

!n )atr mol#'l to b attra#t to anot(r b man% o

)a? intra#tion% ?no)n a% (rogn bon% .atr ma al%o orm (rogn bon% )it( ot(rl#trongati$ atom% . 4(ror, it i% a %ol$nt in )(i#( *olar mol#'l% #anrail i%%ol$.


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:+8; or *'r )atr i% 13197t(ror t( *+ i% 7.


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+i%tor an Dnition%

o'r ta%? i% to r%ar#( t( (i%tor oa#i% an ba%%.

Doing t(i% o' )ill n to n o'tabo't Arr(ni'%, Bron%t Lo)ran L)i%.

B t( n o t( l%%on o' )ill al%on to nition% o a#i% anba%%9 )it( 3am*l% a% 6'ation%.


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Bron%t9Lo)r

Bron%t9Lo)r a#i% an ba%% A Bron%t9Lo)r a#i i% an %'b%tan#

rom )(i#( a *roton can be removed

A Bron%t9Lo)r ba% i% an %'b%tan#t(at #an removea *roton rom an a#i

A %ingl *roton o%nt rall 3i%t ina %ol'tion. A#i% onl rla% *roton%i a ba% #an a##*t it.


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Con"'gat A#i9Ba% air%

In%ta o a oating *roton in%ol'tion, )atr mol#'l% a##*t*roton% to orm (roni'm ion%, +@!

8

4(i% i% %omtim% #all an oxoniumion.


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4(i% i% ana#i

4(i% i% a t(ing

t(at #an a##*ta *roton, it% t(a#i% conjugatebase

(i#( on i% t( ba% an#on"'gat a#i bt)n t(%t)o


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*+

*+ i% #ommonl 3*r%% a% Glog:+8;

It approximates the negative log (base 10) of the molar concentrations

of hydrogen ions H+ (really hydronium ions H0+) in solution

!o a solution of H"l #ith a pH of $%0 has a concentration of hydronium

ions of 1x 10&$ (1'100)

"ompared to a more dilute solution of H"l #ith a pH of %0* #hich has

a hydronium ions concentration of 1 x 10& (1'100*000)%

pH is commonly expressed as logH+,

-ure #ater has H+,.10&/and thus pH./


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o'r Cal#'lator


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*+

*+ i% #ommonl 3*r%% a% Glog:+8;

'r )atr (a% :+8;H197an t('%*+H7.

A#i% (a$ a (ig( :+8; an t('% a lo)*+.

Ba%% (a$ a lo) :+8; an t('% a(ig( *+.

ases contribute H ions #hen they dissociate% 2hese bind to the H+ ions

produced #hen #ater dissociates% 2hus* these H ions 3suc4 up5 the H+

ions in solution* reducing their concentration%

6aH #ith a pH of 1$%0 contributes so many H ions that almost all the H+

ions are bound into #ater molecules* reducing the free H+ (and hydronium)

ion concentration to 1 x 10&1$(1*000*000*000*000 . 1'trillion)


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*+

How do normality

and molarity relate

to pH??

A#i Normalit *+

A#ti# N 2.=

A#ti# .1 N 2.

A#ti# .1 N @.=

+ro#(lori# N .1

+ro#(lori# .1 N 1.1

+ro#(lori# .1 N 2.

S'l'ri# N .@

S'l'ri# .1 N 1.2

S'l'ri# .1 N 2.1

7olarity is the fractions of a mole in solution8 normality is a

measure of the concentration of reactive groups #hich may

affect pH%


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a% to ma%'r *+

Ini#ator % an t%t %tri*% L%% *r#i%

Ea#( ini#ator i% onl goo or a %mall *+

rang


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a% to ma%'r *+

*+ mtrEl#tro ma%'r% +8#on#ntration

M'%t %tanariJ bor '%ing.


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An a#i9ba% *air i% a %t o t)o%*#i% t(at tran%orm into a#(ot(r b gain or lo%% o a *roton


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( i% *+ im*ortant inbiolog

*+ a0#t% %ol'bilit o man %'b%tan#%.

[A]

(mol/L)1 1K1 1K2 1K@ 1K= 1K5 1K 1K7 1K1

Initial pH . 1. 2. @. =. 5. . .7 7.

Final pH .75 7.25 7.75 .1= .25 .2 .2 .2 .27

Dissolved CaCO3

(g perliter oa!id)

5. 5. .51= .= .5= .=7= .=71 .=7 .=7

More calcium carbonate dissolves as pH drops


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*+ a0#t% %tr'#t'r an 'n#tion o mo%t

*rotin% 9 in#l'ing nJm%.


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*+ a0#t% %tr'#t'r an 'n#tion o mo%t

*rotin% 9 in#l'ing nJm%. Man #ll% an organi%m%


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ACIDS AND BASES

A#i% ar #om*o'n% t(at onat*roton% to a %ol'tion, an ba%% ar#om*o'n% t(at a##*t *roton%. 4(

bo *ro'#% a n'mbr o a#i%'ring normal mtaboli%m .

Carbon io3i, )(i#( i% *ro'#

'ring t( o3iation o 'l%, ra#t%)it( )atr to orm #arboni# a#i


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4abl 1. A#i% ro'# b t( Bo

9 Carboni# a#i

9 S'l'ri# a#i

9 (o%*(ori# a#i9 La#ti# a#i

9 Citri# a#i

9 Ammoni'm ion%

9 -ton boi%

9 A#toa#ti# a#i

9 9+ro3b'tri# a#i


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Strong an a? A#i%


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Strong A#i%

Strong a#i% #om*ltl i%%o#iat ina6'o'% %ol'tion.

!nl a ) 3i%t, t( r%t ar )a?. +Cl 9+I

+N!@ 9+Cl!=

+2S!=

+Br


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a? A#i%

a? a#i% onl *artiall i%%o#iatin a6'o'% %ol'tion, t( 6'ilibri'mli% )ll to t( lt.

- 4( A i Di i ti


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-a4( A#i Di%%o#iation

Con%tant A )a? a#i (a% t( ollo)ing

6'ilbri'm&

+A +88 A9

4( 3*r%%ion or t( a#i i%%o#iation#on%tant i%&

-aH

Unit% ar al)a%&


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-a Cont3t

A stronga#i (a% a (ig( -a$al'.

A weak a#i (a% a %mall -a$al'.

Can al%o #on$rt t(% into log%, )(i#(ma?% t( n'mbr% mor managabl.

*-aH 9log1-a

-aH 19*-a

4a?ing log% in$rt% t( $al'%. +ig( *-a

i% a )a? a#i an $i# $r%a.


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*+ o Strong A#i%

For a stronga#i&+A +88 A9

+A totall i%%o#iat%& :+A; H :+8;

U% *+ H 9log:+8;

A bottl o +Cl (a% a #on#ntration o1.22 319@mol m9@. (at i% t( *+


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*+ o a? a#i%

For a weak a#i&+A +88 A9

+A onl *artiall i%%o#iat%.

+8an A9ar orm 6'all. :+8;H:A9;

In o'r 6'ation or -a& :+8;:A9; H :+8;2

D' to t( %mall *artial i%%o#iation ) #an

assume t(at t( 6'ilibri'm #on#ntrationo +A i% t( %am a% t( %tart#on#ntration. 4(i% gi$% '% t( 6'ation&


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*+ o a? A#i%

-aH :+8;2

:+A;

Or

:+8; H -a3 :+A;


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B'0r%

A b'0r #on%i%t% o a )a? a#i an it%#on"'gat ba% t(at #a'% a %ol'tion to r%i%t#(ang% in *+ )(n an a#i or a ba% i%a

I (rogn ion% ar a , t(#ombin )it( t( )a? ba%. I (rogn ion%ar rmo$


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4)o a#tor% trmin t( 0#ti$n%% o a b'0r& it% *-arlati$ to t( *+ o t( %ol'tion an it% #on#ntration.

A b'0r )or?% b%t )it(in 1 *+ 'nit o it% *-a.

Bo 'i% m'%t b *rot#t againt% #(ang% in *+

b#a'% mo%t n3m% ar $r *+ %n%iti$.

In t( long r'n, 3#%% a#i or ba% i% liminat $ia t(?in% an t( l'ng%. In t( %(ort r'n, t( bo i%*rot#t againt% *+ #(ang% b b'0ring %%tm%.

4)o main b'0r% o##'r in t( bloo& t( bi#arbonat b'0ran a b'0r in$ol$ing t( o3gn#arring *rotin(moglobin. 4(% m#(ani%m% normall a#t to maintainbloo *+ bt)n 7.@7 an 7.=@


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B'0r%

Dnition& a %ol'tion t(at r%i%t% #(ang in *+ 4*i#all a mi3t'r o t( a#i an ba% orm o a

#(mi#al

Can b a"'%t to a *arti#'lar *+ $al'

Blood: pH = 7.37-7.45

Too acidic? Increase respiration rate epellin! "#$% drivin!

reaction to t&e le't and reducin! H(concentration.

)cretor* s*stem + ecrete more or less bicarbonate

pH belo, 7.4 in rats + "a"#3in B#) dissociates% carbonates soa

up etra H( to bu''er blood. But bones ,eaened


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B'0r%

( '% t(m EnJm ra#tion% an #ll 'n#tion% (a$ o*tim'm

*+% or *rorman#

Im*ortant antim t( %tr'#t'r an/or a#ti$it o abiologi#al matrial m'%t b maintain


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+o) b'0r% )or?

E6'ilibri'm bt)n a#i an ba%.

E3am*l& A#tat b'0r C+@C!!+ C+@C!!

9 8 +8

I mor +8i% a to t(i% %ol'tion, it%im*l %(it% t( 6'ilibri'm to t(lt, ab%orbing +8, %o t( :+8;

rmain% 'n#(ang. I +8i% rmo$ t(n t( 6'ilibri'm %(it% to t(rig(t, rla%ing +8to ?* t( *+

#on%tant

Li i ( ?i


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Limit% to t( )or?ing rang o ab'0r

Con%ir t( *r$io'% 3am*l& C+@C!!+ C+@C!!

9 8 +8

I too m'#( +8i% a, t(

6'ilibri'm i% %(it all t( )a tot( lt, an t(r i% no longr anmor C+@C!!

9to Oab%orbP +8.

At t(at *oint t( %ol'tion no longrr%i%t% #(ang in *+ it i% '%l%% a%a b'0r.

A %imilar arg'mnt a**li% to t(' r n o t( )or?in ran .


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Contnt%

Ba%i# Mi#al Bio#(mi%tr G AClini#al A**roa#( b Da)n B. Mar?%,(D at all.

Bio?imia -o?tran Da%ar G Sb'a(n?atan -lini% ol( Da)n B.Mar?%, (D ?? G tr"ma(an G

Cta?an 21=


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4+EEND

+AQE A NICE

DA

Acids, Bases and Buffers New

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