Acids, Bases & Salts
CBSE Class 10 – Science
1. What are they?
| What | Everyday Analogy | Tiny Example |
|---|---|---|
| Acid | The taste of a lemon (sour) | Lemon juice |
| Base | Soap feels slippery | A little baking‑soda water |
| Salt | Table salt you sprinkle on food | Common salt (NaCl) |
TL;DR
Acids are sour, bases are slippery, salts are the “neutral” ones.
2. How do we spot them?
| Test | What you see | Why it happens |
|---|---|---|
| Litmus paper | Red → turns blue (acid) Blue → turns red (base) |
Acids give a “blue‑to‑red” reaction, bases give a “red‑to‑blue” reaction. |
| Taste | Sour (acid) Bitter/soapy (base) |
Taste tells you if it’s acidic or basic. Never taste a chemical you don’t know! |
| Feel | Acid: no special feel Base: slippery, like soap |
Bases feel slick because they dissolve in water and make it slippery. |
3. pH – the “sour‑to‑bitter” scale
| pH value | What it feels like | Everyday item |
|---|---|---|
| 0–6 | Sour or very acidic | Vinegar, lemon |
| 7 | Neutral | Pure water |
| 8–14 | Bitter or soapy (basic) | Soap water, baking‑soda solution |
Tip:
A pH meter or pH paper tells you a number; the lower the number, the more sour it is.
4. Neutralisation – when acids & bases meet
| Acid + Base | Result | Tiny Example |
|---|---|---|
| Lemon juice (acid) + Baking‑soda water (base) | Carbon dioxide bubbles, water, and a neutral salt | CO₂ bubbles, little fizz |
Why it works
The acid and base “cancel” each other’s sourness and slipperiness, leaving a plain product (water + salt).
5. Common Acids you see every day
| Name | Where it lives | What it does |
|---|---|---|
| Vinegar (acetic acid) | Kitchen | Flavour, preserves food |
| Lemon juice (citric acid) | Fruits | Tart taste, cleaning |
| Hydrochloric acid (HCl) | Stomach (helps digestion) | Breaks down food |
6. Common Bases you see every day
| Name | Where it lives | What it does |
|---|---|---|
| Baking soda (sodium bicarbonate) | Baking, cleaning | Neutralises acids, makes dough rise |
| Soap (sodium stearyl sulphonate) | Washing | Makes dirt slip away |
| Ammonia (NH₃) solution | Cleaning | Cuts grease |
7. Common Salts you see every day
| Name | Where it lives | What it does |
|---|---|---|
| Table salt (sodium chloride) | Every meal | Adds flavour, preserves |
| Sodium bicarbonate | Baking, cleaning | Acts as a mild base and a salt |
| Calcium carbonate (chalk) | Chalkboards | Adds a smooth surface, neutralises acids |
8. Why do we care about acids, bases & salts?
- Cooking – acids flavour food, bases help dough rise.
- Cleaning – bases dissolve grease, acids dissolve rust.
- Health – our stomach keeps food safe with acids; our body balances acids and bases.
- Industry – makes batteries, soaps, fertilizers, medicines.
9. Safety – a quick checklist
| What to keep in mind | Why |
|---|---|
| Never taste unknown chemicals. | They might hurt your mouth or skin. |
| Wear gloves & goggles. | Even mild acids or bases can sting. |
| Store acids & bases separately. | Mixing them can produce a strong reaction. |
| Keep them out of reach of children. | Kids might try to taste or play. |
10. Quick Quiz (Try it yourself!)
-
What colour does litmus paper turn when you dip it into an acid?
Answer: Blue paper turns red; red paper stays red. -
If you mix vinegar (acid) with baking soda (base), what do you see?
Answer: Bubbles of carbon dioxide gas. -
Name one everyday base and one everyday acid.
Answer: Base – soap; Acid – lemon juice.
11. Summary
| Feature | Acid | Base | Salt |
|---|---|---|---|
| Taste | Sour | Bitter/soapy | Neutral |
| Feel | Normal | Slippery | Normal |
| pH | < 7 | > 7 | ~ 7 |
| Test | Red litmus → blue | Blue litmus → red | No change |
| Everyday use | Food flavour, cleaning | Cleaning, baking | Food seasoning |
Remember:
Acids are the sour ones, bases are the slippery ones, salts are the “neither‑here‑nor‑there” ones that often help bring them together.
Happy studying!