What Turns Red Litmus Paper Blue? Acid-Base Indicators

The rule for remembering litmus tests is simple:

• Bases turn Red Litmus Blue. (Tip: Base = Blue)
• Acids turn Blue Litmus Red. (Tip: Acid = Danger/Red)

If you dip red litmus paper into an acid or neutral solution (like pure water), it will remain red and will not change color.

A base is a chemical compound that, when dissolved in water, yields hydroxide ions (OH⁻). Bases that are highly soluble in water are specifically called alkalis. Bases are chemically opposite to acids. They generally taste bitter, feel slippery or soapy to the touch, and react with acids to form salt and water (neutralization).

Many everyday household items and laboratory chemicals are basic in nature and will turn red litmus paper blue. Examples include:

1. Soap Solution: Highly alkaline, used for cleaning.
2. Baking Soda Solution (Sodium Bicarbonate): A mild base used in cooking.
3. Ammonia: Often found in window cleaners.
4. Sodium Hydroxide (NaOH): A strong laboratory base, also used in drain cleaners.
5. Milk of Magnesia: Used as an antacid to neutralize stomach acid.