📖 Theory & Concepts ▼

1. Acids vs Bases

Property Acids (HCl) Bases (NaOH)
Blue Litmus Turns Red No Change
Red Litmus No Change Turns Blue
pH Range 0 – 7 7 – 14
Taste Sour Bitter
Touch Corrosive Soapy

2. Key Reactions

  • Acid + Metal → Salt + H₂↑ Zn + 2HCl → ZnCl₂ + H₂↑
    H₂ burns with a "pop" sound
  • Acid + Carbonate → Salt + H₂O + CO₂↑ Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂↑
    CO₂ extinguishes a burning splint
  • Acid + Base → Salt + Water HCl + NaOH → NaCl + H₂O
    This is a neutralization reaction
Did you know? Litmus is extracted from lichens. It was one of the first natural pH indicators used by ancient chemists!

🧪 Choose Solution

Interactive Reagents

Procedure

  • 1. Select a solution (HCl or NaOH).
  • 2. Drag litmus paper into the test tube.
  • 3. Add metal or carbonate to observe gas.
  • 4. Use the matchstick to identify evolved gas.

⚠️ Safety

  • Dilute HCl and NaOH are corrosive — NaOH is especially damaging to eyes and skin; wear goggles and gloves and rinse any splash with plenty of water.
  • Always add acid to water, never water to acid, and never taste or touch the chemicals.
  • Hydrogen gas is flammable — do the burning-splint "pop" test with only a small tube of gas, away from other flames.
  • Point the mouth of the test tube away from yourself and others during any reaction.
  • Collect used solutions in the labelled waste container rather than the sink.
Empty Test Tube
Select a chemical to start
Lab Journal
Record observations here...

Results Summary

Litmus: ---
Metal: ---
Carbonate: ---
Gas ID: ---