Question

In an experimental set up, starch is placed in dialysis tubing and suspended in water. When lodine is added to the water, over time the starch solution in the bag turns black, while the color of the water remains the color of diluted iodine. Which of the following most likely occurred?
a. The iodine was not able to cross over the dialysis membrane and the starch turned black.
b. The starch leaked out of the bag, leaving the iodine to oxidize in the bag.
c. The starch stayed in the bag and the iodine leaked into the bag and the reacted with it, turning the solution black.
d. Water oxidized the iodine.

Answer 1

Answer:

c. The starch stayed in the bag and the iodine leaked into the bag and the reacted with it, turning the solution black.

Explanation:

According to the given information, the solution inside the dialysis tubing has starch while water present outside has iodine. The color of the water present outside the dialysis tubing does not change which means that starch did not leak out of the bag and stayed in the bag itself. On the other hand, the starch solution present inside the bag turned black representing the fact that iodine entered the bag. The reaction of starch with iodine produces a blue-black color.