When starch reacts with iodine, why does it create the
characteristic blue-black colour?

Answer Posted / gurudut

Light is reflected or absorbed according to the shape and
form of the molecular complex it enters.

It so happens that the amylose helix with iodine ions in
the helical core is totally absorptive of all the longer
wavelengths of visible light. Colour is only reflection of
particular wavelengths.

The starch iodine test was selected for the entirely
fortuitous reason that it is so diagnostic for chance
reasons alone.

Evidence of the structural nature of the colour lies in
showing that a heated solution of starch-iodine complex
loses its colour at about 70?C and regains it again on
cooling i.e. the amylose denatures and renatures again.

Is This Answer Correct ?    19 Yes 20 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

Explain what are similarities and differences between the transcription process and the replication processes?

678


How do we prepare diborane?

637


what is your aspiration in profession/ career?

2311


What are pentoses?

585


Define Hybridization?

632






Are nucleotides formed of only one type of pentose?

569


During a heart attack, blood flowing to the heart muscle is interrupted by blockage of a coronary artery. How would you expect the metabolism in the heart to change?

2569


What is xylose?

566


What is the importance of the primary structure?

640


One characteristic of the dna molecule is its replication capability. What are the consequences of failures during dna replication?

585


What are enantimorphs and diastereomers ?

635


Two children have a neurological disorder. When cells from the two patients were fused to form heterokaryons containing nuclei from both patients and cultured, the cells displayed normal metabolism. Cells from either patient exhibited abnormal metabolism when cultured separately.what does these results indicate?

1669


What is the rule for the pairing of nitrogen-containing bases in the dna molecule and in the rna?

562


What amount of catalyst is consumed in the reaction it catalyzes?

544


What is the name of the dna duplication process?

534