What are Indicators?
Indicators are substances that change their color when added to acidic or basic solutions. They help determine whether a solution is acidic, neutral, or basic (alkaline) based on the pH level. Indicators are typically weak acids or bases that exhibit different colors in different pH environments.
How Do Indicators Change Color?
- When an indicator is added to a solution, it interacts with the hydrogen ions (H⁺) or hydroxide ions (OH⁻) present.
- In acidic solutions (pH < 7),="" the="" concentration="" of="" h⁺="" ions="" increases,="" which="" can="" cause="" the="" indicator="" to="" change="" to="" one="" />
- In basic solutions (pH > 7), the concentration of OH⁻ ions increases, resulting in a different color change for the indicator.
- The specific color change depends on the type of indicator used, as each has a unique range of pH levels at which it changes color.
Common Indicators
- Litmus:
- Turns red in acidic solutions (pH < />
- Turns blue in basic solutions (pH > 7).
- Phenolphthalein:
- Colorless in acidic solutions.
- Turns pink in basic solutions (pH > 8.2).
- Methyl Orange:
- Red in acidic solutions (pH < />
- Yellow in neutral to basic solutions (pH > 4.4).
- Universal Indicator:
- A mixture of indicators that provides a rainbow of colors to show the exact pH level of a solution.
Conclusion
Indicators are essential tools in chemistry for determining the acidity or basicity of a solution. Their ability to change color based on pH is crucial for experiments, titrations, and everyday applications like testing soil or water quality.

Some special substances are used to tell whether a substance is acidic, basic or neutral. They change their colour accordingly. Example of natural indicators are: turmeric and China rise petals..... Examples of artificial indicators are: phenolphthalein etc.