Color Change by Indicators in Various Acids and Bases

Color Change by Indicators in Acids and Bases (Natural & Synthetic)

Indicators are substances that help us detect whether a solution is acidic or basic. They show color or smell changes depending on the nature (pH) of the solution. Some indicators are synthetic like litmus or phenolphthalein, and some are natural like hibiscus, red cabbage, onion, or vanilla.

1. Litmus

Solution	Litmus Color
Acid (e.g. HCl)	Red
Base (e.g. NaOH)	Blue

2. Methyl Orange

Solution	Methyl Orange Color
Acid (e.g. H₂SO₄)	Red
Base (e.g. KOH)	Yellow

3. Phenolphthalein

Solution	Phenolphthalein Color
Acid (e.g. CH₃COOH)	Colorless
Base (e.g. NH₄OH)	Pink

4. Universal Indicator

pH Range	Color
1–3	Red
4–6	Orange/Yellow
8–11	Blue
12–14	Purple

5. Red Cabbage

Solution	Red Cabbage Color
Acid (e.g. Vinegar)	Red/Pink
Base (e.g. Baking Soda)	Green/Blue

6. Hibiscus Flower Extract

Solution	Hibiscus Color
Acidic	Red
Basic	Green

7. Onion (Smell Indicator)

Solution	Smell Change
Acid	No change in smell
Base	Smell disappears

8. Vanilla Extract (Smell Indicator)

Solution	Smell Change
Acid	Smell retained
Base	Smell disappears

Natural indicators are eco-friendly and can be prepared at home using kitchen materials.

Knowing the pH Scale