Answer
Verified
396k+ views
Hint: Iodine test is used to detect carbohydrates in the compound or material. This reaction gives an intense blue-black color. The triiodide produces an intense blue-black color.
Complete answer:
The presence of starch or iodine in the material is detected by the iodine-starch test. When starch and iodine are mixed it gives an intense blue-black color. Iodometry is the term used to define the interaction between starch and triiodide.
When the triiodide anion (${{I}_{3}}^{-}$ ) comes in contact with the starch it instantly produces an intense blue-black color. When the temperature is increased or the presence of water-miscible organic solvents such as ethanol decreases the intensity of the color. This test has to be done at a normal pH. At very low pH the starch undergoes hydrolysis and this test cannot be performed.
In the iodine test, the starch is used as a self indicator because of the formation of intense blue-black color with triiodide. Starch is also used as an indicator in many redox titrations where triiodide is present. If there is the formation of only iodine ion or only iodide (${{I}^{-}}$ ) the complex will not be formed and the test will not be performed. The intensity of the color of the starch complex is so deep that even the concentration of iodine is as low as 0.00002 M can be detected by naked eyes.
So, the correct answer is “Option B”.
Note: Don’t get confused between glucose and starch. Concentrated iodine must be treated with some reactant like thiosulfate to remove most of the iodine before the addition of starch to the titration.
Complete answer:
The presence of starch or iodine in the material is detected by the iodine-starch test. When starch and iodine are mixed it gives an intense blue-black color. Iodometry is the term used to define the interaction between starch and triiodide.
When the triiodide anion (${{I}_{3}}^{-}$ ) comes in contact with the starch it instantly produces an intense blue-black color. When the temperature is increased or the presence of water-miscible organic solvents such as ethanol decreases the intensity of the color. This test has to be done at a normal pH. At very low pH the starch undergoes hydrolysis and this test cannot be performed.
In the iodine test, the starch is used as a self indicator because of the formation of intense blue-black color with triiodide. Starch is also used as an indicator in many redox titrations where triiodide is present. If there is the formation of only iodine ion or only iodide (${{I}^{-}}$ ) the complex will not be formed and the test will not be performed. The intensity of the color of the starch complex is so deep that even the concentration of iodine is as low as 0.00002 M can be detected by naked eyes.
So, the correct answer is “Option B”.
Note: Don’t get confused between glucose and starch. Concentrated iodine must be treated with some reactant like thiosulfate to remove most of the iodine before the addition of starch to the titration.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
What is the stopping potential when the metal with class 12 physics JEE_Main
The momentum of a photon is 2 times 10 16gm cmsec Its class 12 physics JEE_Main
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Write an application to the principal requesting five class 10 english CBSE
Difference Between Plant Cell and Animal Cell
a Tabulate the differences in the characteristics of class 12 chemistry CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
What organs are located on the left side of your body class 11 biology CBSE
Discuss what these phrases mean to you A a yellow wood class 9 english CBSE
List some examples of Rabi and Kharif crops class 8 biology CBSE