Why Ammonia, Nitric Acid and Sulphuric Acid Matter in Class 10 Chemistry
Ever wondered why your school lab always has those three bottles with strong smells? They’re not just for show – they’re the backbone of many reactions you’ll meet in exams.
💡 In Simple Words: Ammonia, nitric acid and sulphuric acid are three common chemicals. They act as bases, oxidising agents or dehydrating agents, helping you make new compounds in the lab.
Ammonia (NH3) – The Friendly Base
Ammonia is a colour‑less gas that smells like cleaning fluid. In chemistry we call it a “base”, which means it can accept a hydrogen ion (H⁺) from acids. Think of a base as a sponge that soaks up protons, just like a sponge soaks up water.
Key properties
- Molecular formula: NH3
- Physical state: gas at room temperature, but dissolved in water it becomes a clear solution called “ammonium hydroxide”.
- Basicity: reacts with acids to form salts (e.g., NH4Cl when mixed with HCl).
Common reactions
1. Neutralisation with an acid
NH3 + HCl → NH4Cl
Here ammonia grabs a proton from hydrochloric acid and makes ammonium chloride, a white solid.
2. Formation of ammonium salt with sulphuric acid
2NH3 + H2SO4 → (NH4)2SO4
This reaction is used industrially to make fertilizers.
Nitric Acid (HNO3) – The Powerful Oxidiser
Nitric acid is a colourless, highly corrosive liquid that releases brown fumes of nitrogen dioxide (NO2) when heated. In simple terms, it loves to pull electrons away from other substances – that’s what we call an “oxidising agent”. Imagine it as a tiny thief that snatches electrons, making other molecules lose them.
Key properties
- Molecular formula: HNO3
- Physical state: liquid, strong acid, fumes brown gas.
- Oxidising strength: can turn metals into their nitrates and even turn copper green.
Typical uses in class 10 experiments
• Preparing metal nitrates (e.g., Cu + 4HNO3 → Cu(NO3)2 + 2NO2 + 2H2O).
• Testing for the presence of metals – the brown fumes are a tell‑tale sign.
Sulphuric Acid (H2SO4) – The Dehydrating Giant
Sulphuric acid looks like a thick, oily liquid. It’s famous for sucking water out of other substances, so we call it a “dehydrating agent”. Picture it as a very thirsty sponge that pulls water molecules away, leaving the rest of the material dry.
Key properties
- Molecular formula: H2SO4
- Physical state: viscous liquid, very strong acid.
- Special ability: removes water (dehydration) and acts as a strong acid.
Classic demonstration
Mixing sulphuric acid with sugar (C12H22O11) gives a black column of carbon and water vapour – a dramatic way to show dehydration.
Comparing the Three Acids and Base
| Property | Ammonia (NH3) | Nitric Acid (HNO3) | Sulphuric Acid (H2SO4) |
|---|---|---|---|
| Type | Base (accepts H⁺) | Strong acid, oxidiser | Strong acid, dehydrating |
| Physical state | Gas (dissolves in water) | Liquid (fumes NO₂) | Viscous liquid |
| Common lab use | Making ammonium salts | Preparing metal nitrates | Dehydration, making sulphates |
| Safety note | Causes burns, irritating fumes | Corrosive, toxic fumes | Highly corrosive, exothermic with water |
How These Compounds Help You Solve Typical ICSE Questions
When a question asks you to write a balanced chemical equation, remember the “acid‑base” or “oxidation‑reduction” pattern. For ammonia, look for a salt‑forming reaction. For nitric acid, check if the metal is being oxidised to a nitrate. For sulphuric acid, see if water is being removed or a sulphate salt is produced.
Also, keep an eye on the colour clues: brown fumes → nitric acid; no colour change but heat evolution → sulphuric acid; pungent smell → ammonia.
📝 Likely Exam Questions
- Write the balanced equation when ammonia reacts with sulphuric acid.
Answer: 2NH3 + H2SO4 → (NH4)2SO4 - What type of reaction does nitric acid undergo with copper?
Answer: Oxidation‑reduction; copper is oxidised to copper nitrate, nitrogen is reduced to NO2 gas. - Explain why sulphuric acid can turn sugar into black carbon.
Answer: Sulphuric acid removes water from sugar (dehydration), leaving carbon behind. - Identify the product formed when ammonia is added to hydrochloric acid.
Answer: Ammonium chloride (NH4Cl). - State one safety precaution for handling each of the three chemicals.
Answer: Use a fume‑hood for ammonia, wear goggles and mask for nitric acid, add acid to water slowly for sulphuric acid.