Question

What is an indicator ? Write the name of an indicator.

Hint:

For exams, it's crucial to know the color changes for key indicators. A quick summary: \[\begin{array}{rl} \bullet & \text{Litmus: Red in Acid, Blue in Base (Remember BAR: Blue, Acid, Red).} \\ \bullet & \text{Phenolphthalein: Colourless in Acid, Pink in Base.} \\ \bullet & \text{Methyl Orange: Red in Acid, Yellow in Base.} \\ \end{array}\]

Answer 1

What is an indicator?
An indicator is a chemical substance that undergoes a distinct, observable change (usually a color change) when the conditions of its solution change. In the context of acid-base chemistry, an acid-base indicator is a substance that changes color depending on the pH of the solution it is in. It is used to visually determine whether a solution is acidic, basic, or neutral.

Name of an indicator:
A common and simple indicator is Litmus.
\[\begin{array}{rl} \bullet & \text{In an acidic solution (pH < 7): Litmus turns red.} \\ \bullet & \text{In a basic solution (pH > 7): Litmus turns blue.} \\ \bullet & \text{In a neutral solution (pH = 7): It remains purple (the color of the extract).} \\ \end{array}\] Other examples include Phenolphthalein, Methyl Orange, and Turmeric.