When a dialysis tube like we used is filled with a water and

When a dialysis tube (like we used) is filled with (a) water and some drops of phenolphthalein and immersed in a beaker filled with a mixture of 200 mL of water and 10 drops of 1M NaOH or a starch solution and immersed in a beaker filled with a mixture of 200 mL of water and 40 drops of iodine: What should happen to the tube? What should happen to the beaker solution? What happens when red

Solution

5). (a). Phenolphthalein is an acid-base indicator, which turns yellow in the acidic pH and turns wink in the basic pH. It appears red in color at neutral pH. As the NaOH is a base, the solution turns to pink colour indicating the basic pH.

(b). The presence of starch can be tested by the iodine test (Lugol’s reagent). If only starch is present, the sample turns dark brownish black.