Question

Two potato cubes (1 mm3 and 2 mm3) were placed in a solution of iodine. The absorption of iodine can be visualized by observing the purple color from the iodine and starch reaction. Why would the smaller (1 mm3) be completely purple in a shorter amount of time?

Answer 1

Answer:

because the smaller potato cube has a smaller volume to area ratio that means smaller absorption time.

Step-by-step explanation:

there are 2 things to consider:

1°) if the iodine enters at constant rate to the cube, the time required to completely absorb all the iodine is proportional to the mass of the potato cube ( more mass that is required to absorb, means more iodine should enter the cube at same rate and therefore more time) . also, the mass of the potato is proportional to the volume of it (assuming constant density)

2°) if we consider 2 potatoes with same mass, the time required is inversely proportional to the area of contact with the solution of iodine ( more area means more iodine is able to enter per mm2 of potato's surface with the same mass and consequently less time)

therefore, the time is proportional to the ratio of volume and area of the cube. Since the smaller cube has a smaller ratio, takes less time to be completely purple

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