3. Definition of
Indicator
Indicator is a chemical
substrate that added into a
titration which give a change of
color when the endpoint
reached.
Indicator usually used at
a reaction of titration that
the change is invisible or
4. Yodometri
Indicator
Titration in yodometric actually
can do without the addition of
indicator from outside because the
color that produce by I2 that
titrated by Tio will be dissolved
when endpoint reached.
Generally, first the change of the color is dark
brown, then become light brown, then turn into
yellow, light yellow, until in the end the color of
solution will be disappear.
When it observed, the color is
5. There are several types of
indicators may be used in redox
titration. Among them are the
specific indicators, are
substances that cause reactions
in a specific way with one of the
reactants in the titration to
produce colors such as dark
blue starch with iodine.
7. Kanji can be separated
into two primary
components such amylose
Amylose
( ) which long and straight
chain, is abundant in potato
starch , and gives blue color
with Yod. And amylopectin
Amylopectin
( ) which has a long chain
but branched, and form a
8. In daily language, word
“starch” always mixed with
“flour” and also “kanji”.
Starch is a primary compose of
flour. Flour can be may not
only contain pure starch, it can
be mixed or blended with
protein, vitamins, and other
materials contained in the
9. Co l o r e d c o mp l e x
f o r ma t i o n me c h a n i s m
i s n o t p r e c i s e l y
k n o wn . Ho we v e r , t h e
i o d i n e mo l e c u l e s
a r e h e l d o n t h e
s u r f a c e o f a my l o s e , a
s t a r c h e l e me n t .
E l e me n t s o f o t h e r
s t a r c h a my l o p e c t i n
f o r m a c o mp l e x t h a t
i s r e d d i s h (v i o l e t )
10.
11. The main advantage of kanji is cheap.
But the disadvantages, such as:
1. Insoluble in cold water
2. Unstable suspense in water
3. With Iod give a complex that insoluble in
water, so kanji can’t be added in the
beginning of the titration.
Kanji can’t be added into a highly acidic
medium because it can occurs hydrolysis
of the kanji. And also the addition of the
etanol 50% or more because the color
12. The Example Of
Yodometri Titration
Y o d o me t r i i s
t i t r a t i on wi t h r e d o x
me t h o d . T h i s
t i t r a t i on i s i ndi r e c t
t i t r a t i on, wh e r e
ne e de d ot h e r
s ubs t a nc e be f o r e
t i t r a t e d wi t h T i o
s ol ut i on.
An d t hi s i s a n
e x a mp l e of s ubs t a nc e
13. Th i s p r o c e d u r e b a s e
o n r e a c t i o n b e t we e n
c h l o r a t a n d i o d i d e
- - -
w i t ClO 3 6I
h c o n c Cl n
6H e t3Ir2 a 3HeO
t 2 d
c h l o r i d e a c i d :
i o d t h a t p r o d u c e d a r e
t i t r a t e d wi t h Ti o
s o l u t i o n .
I n o t h e r me t h o d e ,
t h ClO 3 6Br - c 6H o r Cl - t 3Br 2 3Hs O
i s- h l a i 2
14. Determination The Content of
Cu (II) in CuSO4.5H2O by “De
Haens” Way
In acidic conditions, Cu (II) can be
reduced to CuI2 which then decompose into
Cu2I2 and I2. Thereafter, the free I2 titrated
with Na2S2O3 (sodium thiosulfate) and
starch indicator when approaching the
endpoint. Cu (II) reduced by KI. The end
point of this designation is from blue to
colorless and milky white precipitate
formed.
15.
16. Determination of
Normality of Na2S2O3
with BBP KIO3
In acidic conditions, can be
oxidized by KIO3 KI to iodine (I2)
that have free brown. Free I2 then
titrated with Na2S2O3 until a
slight yellow color. The addition
of starch as an indicator of the
blue and make the solution
obtained colorless endpoint.
17. KIO 3 5KI 6HCl 6KCl 3I 2 3H 2O
I2 2Na 2S2 O3 2 NaI Na 2S4 O 6