Question

What is an indicator? Write the names of two indicators.

Hint:

Methyl orange is another common synthetic indicator (red in acid, yellow in base).

Answer 1

Step 1: Understanding the Concept:
Indicators are chemical tools used to test the nature (acidic or basic) of a solution.

Step 2: Detailed Explanation:
An acid-base indicator is a dye or a mixture of dyes that exhibits a noticeable color change depending on whether it is in an acidic or a basic environment.
They are used to determine the pH or to find the endpoint of an acid-base titration.
Two common examples are:
1. Litmus: A natural indicator (from lichens) that turns red in acid and blue in base.
2. Phenolphthalein: A synthetic indicator that is colorless in acidic solutions and turns pink/red in basic solutions.

Step 3: Final Answer:
An indicator is a substance showing color change based on acidity. Litmus and Phenolphthalein are two examples.