Litmus paper is a simple tool made from plant extracts. It changes color when it touches acids or bases:

• Blue litmus paper → turns red in acid
• Red litmus paper → turns blue in base
• If there is no change, the substance is neutral (like water)

What You Need

• Blue litmus paper
• Red litmus paper
• Various substances to test (lemon juice, vinegar, soap solution, water, baking soda solution)
• A clean tray or table

Steps to Follow

1. Prepare your samples — Put small amounts of each substance in separate clean containers or on a clean tray.

2. Test with blue litmus paper — Dip the blue litmus paper into the first substance. Observe if it changes color.

3. Test with red litmus paper — Dip the red litmus paper into the same substance. Observe if it changes color.

4. Record your results — Write down what you see for each substance:

5. Repeat — Test all your substances using the same steps.

Common Acids

• Lemon juice and orange juice (citrus fruits)
• Vinegar (used in cooking)
• Yogurt (contains lactic acid)
• Tomato juice

Common Bases

• Soap (used for washing)
• Baking soda (used for cleaning and cooking)
• Lime (used by farmers to treat acidic soil)
• Antacid tablets (medicine for stomach acid)

• Acids turn blue litmus paper red.
• Bases turn red litmus paper blue.
• Neutral substances do not change litmus paper.
• Litmus paper helps us identify acids and bases in everyday substances.

In Tanzania, farmers in places like Arusha and Mbeya often test their soil to see if it is too acidic for growing crops. They use simple indicators like litmus paper or visit agricultural offices to check the soil. If the soil is too acidic, they add lime (a base) to neutralize it so that crops like maize and coffee can grow well. This simple test helps farmers decide how to treat their land for better harvests.