Question

question
how are you going to determine if iodine and/or starch diffuse across the dialysis tubing?
select all of the correct statements.
a. if only iodine is able to diffuse across the membrane, the solution in the dialysis tubing bag will look dark purple.
b. if only starch is able to diffuse across the membrane, the solution in the dialysis tubing will look dark purple.
c. if both iodine and starch are able to diffuse across the membrane, both the dialysis tubing and the beaker will look dark purple.

Explanation:

• Option A: Iodine reacts with starch (if present in the dialysis tubing) to form a dark - purple complex. If only iodine diffuses into the tubing (where starch is already present), the solution in the dialysis tubing bag will turn dark purple.
• Option B: Starch is a large - molecule. If only starch diffuses (which is not likely as starch is a large polymer and dialysis tubing is semi - permeable, usually allowing small molecules like iodine to pass more easily), but if we assume for the sake of the reaction, starch alone cannot cause a color change. The color change (dark purple) is due to the iodine - starch complex.
• Option C: If both iodine and starch can diffuse. Let's assume the dialysis tubing has starch initially and the beaker has iodine initially. If iodine diffuses into the tubing (where starch is), the tubing solution turns dark purple. If starch diffuses out (unlikely due to size, but if it does) and there is iodine in the beaker (from the initial setup or if it can move back), the beaker solution will also turn dark purple.

Answer:

A. If only iodine is able to diffuse across the membrane, the solution in the dialysis tubing bag will look dark purple.
C. If both iodine and starch are able to diffuse across the membrane, both the dialysis tubing and the beaker will look dark purple.