Living Environment Regents Practice Test

After adding starch indicator solution, what is the expected final color of side Y in a dialysis experiment?

1. Black

2. Amber

3. Transparent

4. Blue

The correct answer is: Amber

In a dialysis experiment involving starch and an indicator solution, the expected color change can be understood by considering the properties of starch and the behavior of the indicator. Starch indicator solution is used to detect the presence of iodine, which reacts with starch to produce a characteristic blue-black color. When starch is present in the dialysis bag and iodine is in the surrounding solution, iodine molecules can diffuse through the dialysis membrane into the starch solution, leading to a color change. If side Y, where the starch indicator is added, initially contains iodine, the reaction with starch will create a blue-black coloration. However, if side Y is primarily composed of the starch solution without excess iodine, it may not develop the intense blue-black color, potentially resulting in an amber or yellow hue, as the blue-black can sometimes dominate depending on the concentration of starch present. In a scenario where excess starch is present without iodine entering from the side with a different concentration, the expected final color could lean towards an amber, reflecting a more dilute starch solution where the indicator doesn't fully react in the concentration present. Thus, the final color of side Y should be interpreted in the context of both the presence of starch and the extent of iodine diffusion. If the side primarily consists of starch that hasn't