Konduktometri - Copy

KONDUKTOMETRI

KONDUKTOMETRI

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K Konduktometri ---onduktometri

---

 _{KonduktometriKonduktometri& & '$to($ '$to($ anali)i) anali)i) kon)$ntra)i kon)$ntra)i *$r(a)arkan*$r(a)arkan}

 +$ngukuran

 +$ngukuran kon(ukti,ita) kon(ukti,ita) yang yang (iha)ilkan (iha)ilkan (ari (ari )$+a)ang )$+a)ang $l$ktro(a$l$ktro(a in$rt ($ngan lua) +$na+ang +a(a jarak t$rt$ntu.

in$rt ($ngan lua) +$na+ang +a(a jarak t$rt$ntu.



 _{PrinsipPrinsip&&}

1.

1. !ay!aya a hanhantar tar li)tli)trik rik $$ru+ru+akaakan -n -ung)ung)i i konkon)$n)$ntratra)i )i larlarutan utan anaanalit lit yanyangg (iukur.

(iukur. 2.

2. S$S$akiakin n u(u(ah ah larlarutautan n anaanalit lit t$rt$rioniioni)a))a)i i aaka ka (ay(aya a hanhantar tar li)li)tritrikk )$akin *$)ar.

)$akin *$)ar. 3.

3. !ay!aya hana hantar ltar li)tri)trik ik uncuncul kaul kar$nr$na a(aa a(anya +nya +$rg$rg$ra$rakan ikan iononion (ion (alaala larutan analit.

larutan analit.

Prinsip Konduktometri

Prinsip Konduktometri

1. Sumber listrik 

  Su*$r li)trik $nggunakan aru) *olak *alik AC. r$ku$n)inya )$kitar 1000 . Su*$r li)trik j$ni) ini akan $icu unculnya hantaran aru) li)trik $lalui larutan )$*agai aki*at a(anya +$rg$rakan ion (ari analit.

2. Sel

S$l t$r(iri (ari )$+a)ang $l$ktro(a yang t$r*uat (ari *ahan yang )aa yang k$u(ian (ila+i)i ($ngan loga 5t untuk $ningkatkan $-$kti,ita) +$rukaan $l$ktro(a.

2. Tahanan Jembatan

 6$*atan h$at)ton$ *$r-ung)i untuk $ngukur tahanan larutan.

(iana&

8& (aya hantar li)trik )i$$n) atau Ω 1

R& ha*atan Ω

K& (aya hantar j$ni) Ω 1.c1

A& lua) +$na+ang $l$ktro(a l & jarak k$(ua $l$ktro(a

Daya Hantar Listrik

l  A k  R  1 8 _{= =}

 _{Daya hantar ekivalen}& !aya hantar li)trik yang (iha)ilkan ol$h 1 gra $ki,al$n at t$rlarut (ala )i)t$ larutan $l$ktrolit yang $iliki )$+a)ang $l$ktro(a ($ngan jarak k$(ua $l$ktro(a )$*$)ar 1 c.

 olu$ larutan c3 yang $ngan(ung 1 gra $ki,al$n at t$rlarut&

atau

 !$ngan jarak antara k$(ua $l$ktro(a )$*$)ar 1 c&

 _S$hingga

"$r(a)arkan )i-at (aya hantar li)triknya larutan (i*agi $nja(i (ua yaitu&

1. Larutan elektrolit& :arutan yang a+u $nghantarkan li)trik kar$na $iliki ionion yang *$rg$rak *$*a) (i (ala larutan yang nantinya akan $nja(i  +$nghantar. :arutan $l$ktrolit (i*agi $nja(i (ua yakni&

a. Larutan elektrolit kuat& larutan yang (a+at $nghantarkan aru) li)trik ($ngan  *aik kar$na at t$rlarut t$rurai )$+urna.

Contoh& a)a kuat Cl 2S;4 35;4 N;3 < *a)a kuat Na; Ca;2

'g;2 :i;2 gara NaCl.

 *. Larutan elektrolit lemah& larutan yang (a+at $nghantarkan aru) li)trik ($ngan l$ah kar$na at t$rlarut t$rurai )$*agian.

Contoh& a)a l$ah C3C;; CN 35;4 *a)a l$ah =Al;3 N4;>

gara N4CN.

2. Larutan non elektrolit& :arutan yang ti(ak a+u $nghantarkan li)trik.

Larutan Eektroit dan Non eektroit

Larutan Elektrolit Larutan non elektrolit

!a+at $nghantarkan li)trik ?i(ak (a+at $nghantarkan li)trik   @at t$rlarut (a+at t$rioni)a)i @at t$rlarut ti(ak (a+at t$rioni)a)i !$rajat ioni)a)i  B 1 atau 01 !$rajat ioni)a)i  B 0

:a+u (a+at $nyala t$rang atau r$(u+ (an a(a g$l$*ung ga)

:a+u ti(ak $nyala (an ti(ak a(a g$l$*ung ga)

Contoh& NaCl C₃C;; ₂S;₄ Contoh& C₂_D; C_%₁₂;_% C;N₂₂

1. Luas permukaan elektroda

S$akin lua) +$rukaan $l$ktro(a )$akin *anyak ion yang (a+at  *$rint$rak)i ($ngan +$rukaan $l$ktro(a )$hingga kon(ukti,ita)

)$akin *$)ar.

2. Jarak kedua elektroda

S$akin jauh jarak k$(ua $l$ktro(a )$akin *$)ar $n$rgi yang (i*utuhkan ionion untuk )a+ai k$ $l$ktro(a )$hingga kon(ukti,ita) )$akin k$cil.

3. Konsentrasi larutan

S$akin *$)ar kon)$ntra)i larutan )$akin *anyak julah ionion yang  *$ra(a (ala larutan )$hingga kon(ukti,ita) )$akin *$)ar.

. Temperatur

K$naikan t$+$ratur $ningkatkan +$rg$rakan ionion (ala larutan )$hingga kon(ukti,ita) larutan $ningkat.

!. "obilitas ionik 

S$akin u(ah ionion *$rg$rak kon(ukti,ita) )$akin *$)ar. "$*$ra+a -aktor yang $+$ngaruhi o*ilita) ionik (iantaranya&

a. K$kuatan :i)trik atau electrical force ,  k$kuatan yang (a+at $nci+takan *$(a +ot$n)ial (i antara k$(ua $l$ktro(a )$hingga ion  *$rg$rak $nuju k$ )alah )atu $l$ktro(a.

 *. E-$k El$ktro-or$tik  a+a*ila uatan yang *$rla#anan $ng$lilingi ion )$hingga t$r*$ntuk (ua la+i)an uatan yang $ngha*at o*ilita) ionik (an $nurunkan kon(ukti,ita) larutan.

c. E-$k R$lak)a)i a+a*ila )alah )atu ion (itarik ol$h ion ($ngan uatan yang *$rla#anan (i *$lakang ion t$r)$*ut untuk $njauhi kutu* )$hingga $ngha*at o*ilita) ionik.

 Titrasi Konduktometri

 '$to($ kon(ukto$tri (a+at

(igunakan untuk $n$ntukan titik $ki,al$n )uatu $to($ titra)i.

  No n$$( o- in(icator 

 _{Color$( or (ilut$ )olution) or tur*i( )u)+$n)ion) can *$ u)$( -or}

titration).

 ?$+$ratur$ i) aintain$( con)tant throughout th$ titration.

 En( +oint can *$ ($t$rin$( accurat$ly an( $rror) ar$ inii$( a) th$ $n( +oint i) *$ing ($t$rin$( gra+hically.

?itra)i a)a l$ah C3C;;

($ngan *a)a kuat Na;.

?itra)i a)a l$ah C3C;; ($ngan *a)a l$ah

N4;.

a ?itra)i a)a kuat Cl ($ngan *a)a kuat Na; * ?itra)i a)a kuat Cl ($ngan *a)a l$ah N₄;

c ?itra)i a)a l$ah C₃C;; ($ngan *a)a kuat Na; ( ?itra)i a)a l$ah C₃C;; ($ngan *a)a l$ah N₄;

$ Ca+uran a)a kuata)a l$ah ($ngan *a)a kuat

I‑ Titration of Strong Acid with Strong Base: e.g. HCl ≠ NaOH

HCl + NaOH → NaCl + H₂O

H+ _{+ Cl}- _{+ Na}+ _{+ OH}- _{→ Na}+ _{+ Cl}- _{+ H} 2O

 Before titration the conductance is high which is due to HCl  H+ + Cl-mobility of H+ is 35 and that of Cl-_{ion is !3"}

 #$on addition of NaOH the H+ _{ion reacts with OH}- _{ion to form the %ery wea&ly ioni'ed water}

molecule"

 (his means that the H+ _{ion is remo%ed from the medium and re$laced by Na}+ _{ion which has a}

mobility of )3* thus a

continuous abru$t decrease in conductance  occurs during the titration till the end $oint"

 Beyond the end $oint there is excess Na+

and OH- _{ions with )3 and , mobility due to}

 continuous addition of NaOH

 .o there is continuous increase in conductance  and the cur%e will ha%e a / sha$e 0 the end

 $oint is the minimum of the cur%e"

- H+ + Na+ + OH -+ Na+ E%p %

- Titration of wea! acid with strong "ase e.g. CH#COOH ≠ NaOH

CH₃COOH + Na+ + OH- → CH

3COO- + Na+ + H2O

Before titration low initial conductance is obser%ed due to low H+ obtained during dissociation of

weak CH₃COOH"

1uring titration we can obser%e slight decrease of conductance due to consum$tion of H+ "

1uring $rogress of titration we can obser%e slight increase in conductance due to the $resence of CH3COO- (41) &

Na+ (43) and nearly constant H+ due to the

buffer action of the $roduced CH3COONa and the remaining

CH3COOH"

 fter end $oint ecess NaOH will lead to increase in conductance due to increasing

+ CH_#COO -+ Na+ + OH -+ Na+ E%p %

#- $i%t&re of strong acid and wea! acid aganist

strong "ase.

e.g. HCl'CH#COOH (i% ≠NaOH

(he initial conducti%ity is high it is due to HCl which by common ion effect su$$ress the ioni'ation of CH3COOH"

 #$on titration* decrease in conducti%ity occurs due to re$lacement of H+ ion with

mobility 35

by Na+ ion with mobility )3 0 till all the H+

ions from HCl are neutrali'ed"

CH3COOH will thus ioni'e and

react with NaOH"

(he change in conducti%ity will ta&e $lace in similar way as described abo%e"

)- *receitation Titrations



6t is im$ortant to choose the suitable titrant which gi%es

shar$ change at the e7ui%alence $oint"



(itrant must ha%e mobility that %aries greatly from the

sam$le because the products are weakl !o"!#able

leading to decrease in conductance during titration till the

end$oint"

e.g. Titration of NaCl ≠ AgNO

#

NaCl + gNO

3 

 gCl + NaNO

3

Na

+

 + Cl

_‑

 + g

+

 + NO

3‑ 

 gCl + NO

3

-

 + Na

+



1uring titration of NaCl against gNO

3

0 g

+

 $reci$itate Cl

-

 as

 gCl and NO

3-

 re$lace Cl

-

 in the medium"



 s mobility of NO

3-

 4!"5 is nearly e7ual that of Cl

-

4!8"3 we

obser%e nearly no change in conductance during titration"



 _{fter com$lete $reci$itation of Cl}

-

 0

e g

+

 48", and NO

3-

 4!"5 will

increase conductance of solution"

- Cl

-+ NO_#

-+ Ag+

-e.g. Titration of BaCl_ ≠ Na_SO₎ BaCl₂ + Na₂.O₎Ba.O ) +2 NaCl Ba2+ _{+ 2Cl‑ + 2Na}+ _{+ .O} ) 2_‑  Ba.O₎ +2Cl‑ + 2Na +

1uring titration of BaCl₂ against Na₂.O₎ 0 .O₎2- _{$reci$itate Ba}2+_{as Ba.O}

) i"e92

Ba2+ _{4mobility 83"8  is re$laced by Na}+ _{4mobility )30 therefore conductance is}

decreased during titration"

 fter com$lete reaction conductance is increased due to addition of e

Na+ _{4)3 and .O}

)2- 4mobility of : .O)2-

after the end $oint"

(he cur%e is / sha$e its minimum is the end $oint " 6t is obtained by etra$olation  of the two arms of the cur%e"

- Ba+

+ Na+

+ SO₎