

Indicator Color Changes and pH Ranges Chart
The concept of pH color change is essential in chemistry and helps explain how acids, bases, and neutral substances can be quickly identified visually using chemical indicators. This process is crucial in laboratories and daily life for understanding the properties of different solutions.
Understanding pH Color Change
pH color change refers to the visible shift in the color of a solution when a pH-sensitive chemical indicator is added. The indicator changes color based on the pH (acidity or alkalinity) of the solution. This concept is important in areas like acid-base identification, titrations, and environmental testing.
How Do pH Indicators Work?
pH indicators are special chemicals, usually weak acids or bases, that exhibit different colors in their acidic and basic forms. When added to a solution, these indicators react with hydrogen ions (H+) or hydroxide ions (OH-). The structure of the molecule changes, absorbing and reflecting light differently. As a result, the color seen by our eyes changes with the solution's pH. For example, litmus turns red in acid (pH less than 7) and blue in base (pH more than 7).
Common Indicators and Their pH Range for Color Change
Here’s a helpful table to understand pH color change for popular indicators:
pH Color Change Chart
Indicator | Acid Color | Base Color | Transition pH Range |
---|---|---|---|
Litmus | Red | Blue | 4.5 - 8.3 |
Phenolphthalein | Colorless | Pink | 8.2 - 10.0 |
Methyl Orange | Red | Yellow | 3.1 - 4.4 |
Bromothymol Blue | Yellow | Blue | 6.0 - 7.6 |
Universal Indicator | Red (pH 1) | Violet (pH 14) | Entire scale 1 - 14 |
Chemical Formula / Reaction of pH Color Change
For an indicator (e.g., HInd):
HInd (acid form) + OH- → Ind- (base form) + H2O
The acid form and base form have different colors. The equilibrium between these forms (depending on pH) is what causes the pH color change.
Worked Example – Observing pH Color Change
Let’s understand the process step by step:
1. Take a few drops of universal indicator solution in a clean test tube.
2. Add a small amount of hydrochloric acid (acidic) – note the color turns red/orange.
3. Separately, add sodium hydroxide (basic) – observe the color turns blue/purple.
4. For neutral water, the color will be green (pH = 7).
Final Understanding: The color difference directly reveals the pH level of each solution.
Real-World Applications
The concept of pH color change is widely used in laboratories for titrations, in swimming pools for water quality checks, in cosmetics like pH color changing lip gloss, and in environmental science for testing soil or water. Diagnostic strips used for medical urine tests also work on pH-based color change. Vedantu often explains how such applications relate to your board syllabus and practical life.
Practice Questions
- Define pH color change and give an example with an indicator.
- Why do indicators show different colors at different pH values?
- How is pH color change used in acid-base titration?
- Complete this: Phenolphthalein is _____ in acid and _____ in base.
Common Mistakes to Avoid
- Confusing pH color change range of one indicator with another (e.g., phenolphthalein and methyl orange).
- Using old or contaminated indicator solutions, leading to incorrect color results.
- Not memorizing the correct color transitions and pH range for main indicators before exams.
More on pH and Indicators
- pH of Samples – See how pH is measured in labs.
- Chemical Indicators – Learn types, reactions, and why they change color.
- Acid-Base Titration – Role of pH color change in calculations.
- Litmus Paper – Classic blue/red test for acids and bases.
- Phenolphthalein – Detailed color change data and exam tips.
- Importance of pH in Everyday Life – Find out where pH color change matters daily.
In this article, we explored pH color change, its definition, real-life relevance, and how to solve related problems. Continue learning with Vedantu to master chemistry indicators, pH calculations, and exam skills with confidence.
FAQs on What is pH Color Change?
1. What is pH color change in chemistry?
2. Which indicator changes color at what pH values?
3. What is the pH range for phenolphthalein's color change?
4. How does pH paper show different colors?
5. Why do acids and bases cause different color changes?
6. What is the pH color change of phenolphthalein?
7. How can I use pH indicators to identify acids and bases?
8. What are some common pH indicators used in experiments?
9. What is the significance of pH color change in acid-base titrations?
10. What are some real-world applications of pH color change?
11. Can pH indicators be used to measure the pH of all solutions?

















