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 both iodine and starch are able to diffuse across the membrane, both the dialysis tubing and the beaker will look dark purple.

b. if only iodine is able to diffuse across the membrane, the solution in the dialysis tubing bag will look dark purple.

c. if only starch is able to diffuse across the membrane, the solution in the dialysis tubing will look dark purple.

Explanation:

• Option A: Iodine (a small molecule) and starch (a large molecule, but if both diffuse, iodine in beaker/starch in tubing and vice versa—iodine + starch gives purple. So both areas with both substances would be purple. Correct.
• Option B: If iodine diffuses into the tubing (where starch is), iodine + starch = purple. So tubing solution (with starch) + iodine (diffused in) becomes purple. Correct.
• Option C: Starch is large; dialysis tubing (like a semipermeable membrane) typically doesn’t let large starch molecules diffuse. Even if we assume it could, iodine (needed for purple) would need to be in the tubing or starch in beaker with iodine. If only starch diffuses out, beaker (with iodine) would be purple, not tubing. So incorrect.

Answer:

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