⚡ Quick Revision
One-page cheat sheet · Read this 1 day before the test
🍋 ACIDIC
- Sour taste
- Blue litmus → RED
- Lemon, vinegar, curd, tamarind, amla
🧼 BASIC
- Bitter, soapy
- Red litmus → BLUE
- Soap, baking soda, lime water
⚪ NEUTRAL
- Neither sour nor bitter
- No change in litmus
- Pure water, sugar, salt soln.
🌈 Indicator Colour Chart
| Indicator | Acid | Base |
|---|
| Blue litmus | Red 🔴 | Blue (no change) |
| Red litmus | Red (no change) | Blue 🔵 |
| Turmeric | Yellow (no change) | Red 🔴 |
| Red rose extract | Red/Pink | Green 🟢 |
| Phenolphthalein | Colourless | Pink 💗 |
| China rose (gudhal) | Dark pink | Green |
🧪 Acids You Must Know
| Acid | Found in |
|---|
| Citric | Lemon, orange |
| Acetic | Vinegar |
| Lactic | Curd |
| Acid | Found in |
|---|
| Tartaric | Tamarind, grapes |
| Formic | Ant sting |
| Ascorbic (Vit C) | Amla, citrus |
⚖️ Neutralisation — THE Key Equation
Acid + Base → Salt + Water + Heat ⚡
Where it's used:
- 🐜 Ant sting → moist baking soda (base) cancels formic acid
- 🤢 Acidity → antacid neutralises stomach HCl
- 🌱 Acidic soil → add lime · Basic soil → add manure
- 🏭 Factory waste → add lime before releasing into rivers
- 🦷 Toothpaste → neutralises acid made by mouth bacteria
🔑 Must-Remember Keywords
Indicator
Litmus
Lichen
Olfactory indicator
Phenolphthalein
Neutralisation
Antacid
Formic acid
Lime water
Hydrangea
🧠 Memory Tricks
- Litmus rule: Acid is Angry → turns blue Red. Base is Bouncy → turns red Blue.
- Turmeric: works on bases only — "Turmeric Targets Bases".
- Rose: Acid keeps it Rose-red, Base makes it Green.
- Olfactory: "olfactory" = nose 👃 → smell changes (onion, vanilla).
- Equation: "A + B = SWH" → Salt, Water, Heat.
⚠️ Common Mistakes to Avoid
- Don't write "all bitter things are bases" — coffee & bitter gourd are not!
- Phenolphthalein is synthetic, NOT natural.
- Turmeric does not change colour in acids.
- Salt formed in neutralisation is not always neutral — depends on the acid & base.
- Never forget to mention "Heat" in the neutralisation equation.
🎓 You're ready when you can: ① name 3 acids & their sources · ② name 4 indicators & their colour changes · ③ write the neutralisation equation · ④ give 3 real-life uses of neutralisation.