Question

why do starch give blue black colour with iodine?

Answer 1

547starchcoil.gif

Chemical Test for Starch or Iodine

Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. The iodine molecule slips inside of the amylose coil.

Answer 2

Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. In the Iodine test , Iodine dissolved in aqueous solution of Potassium Iodide (KI) reacts with starch producing a bluish colour.

So present in the solution is the tri-iodide ion.

Hope this helps ☺️☺️