Final answer:
Alizaran S Red is a pH indicator that changes color depending on the pH level of the solution, demonstrating whether the solution is acidic or basic.
Step-by-step explanation:
Alizaran S Red is used as a pH indicator. Acid-base indicators like Alizaran S Red are organic substances that change color at a specific pH due to changes in the hydronium ion concentration. A common example of an acid-base indicator behavior is observed with phenolphthalein, which is colorless in acidic solution but turns pink in basic solution when the hydronium ion concentration falls below a certain level. Alizaran S Red demonstrates this type of color change in response to the pH of the solution it is in, thus indicating its acidity or basicity. We can use this distinct color to signal the presence of excess iodine as a titrant, a change in color from colorless to blue, or the completion of a reaction consuming iodine as the titrand, a change in color from blue to colorless.