When brown iodine is exposed to starch it turns dark purple. In an experiment, you placed a cornstarch solution in a small plastic bag. Next, you placed the bag in a beaker of water containing 10 drops of iodine. If the solution in the plastic bag turned dark purple (Select all that apply)
a) the plastic bag was permeable to cornstarch.
b) the plastic bag was permeable to iodine.
c) the iodine moved into the plastic bag.
d) the cornstarch moved into the beaker.
e) the plastic bag was selectively permeable.

Respuesta :

Answer:

b) the plastic bag was permeable to iodine

the plastic bag was selectively permeable

the iodine moved into the plastic bag.

the plastic bag was permeable to cornstarch.

Explanation:

The experimental set up represented the concept of osmosis.That is  the movement of water  molecules from the region of higher  water potential to region of lower water potential through a semipermeable membrane(a  cell membrane which only allows water and certain molecules to pass through,but restrain other molecules through its pores.

Generally potassium iodine test is the standard test for starch.

Therefore, in the question,water moves iodine molecules as iodine solution(from high water potential) to move across the paper bag(semi permeable membrane) to the reach the corn solution.(low water potential,high solute potential).This turns the starch in the corn solution  blue-black/purple.

If the solution in the plastic bag turned dark purple:

  • the plastic bag was permeable to iodine. That is option (B)
  • the iodine moved into the plastic bag.  That is option (C)
  • the plastic bag was selectively permeable.  That is option (E)

To test for the presence of starch in a solution, iodine solution is used. This gives a blue-black coloration which occurred due to the formation of a starch-iodine complex.

From the above experiment, the plastic bag which contains the corn starch solution, separates the solution from water containing 10 drops of iodine.

The turning of the solution, inside the plastic bag, into blue black signifies the formation of starch-iodine complex between the cornstarch solution the iodine water.

The reaction was able to occur because the plastic bag, which is selectively permeable to iodine, allowed the movement of iodine from the beaker of water into it. This is called diffusion.

Therefore, if the solution in the plastic bag turned dark purple it means that the plastic bag which is semi permeable allowed the movement of iodine into it.

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