Chemical Kinetics രാസഗതികം
The chapter opens in a place you know well: the home kitchen, which is really a small chemistry laboratory. Ice melts and water boils there (physical changes), but rice cooks, milk turns into curd and the dosa batter ferments (chemical changes). First you will learn the signs of a chemical change: a change of colour, a gas, a smell, a precipitate, heat. Then you will sort reactions into four families: combination, decomposition, double decomposition and displacement. The second half of the chapter asks a new question: how fast does a reaction go? Fireworks explode in a moment, but an iron gate takes months to rust in the monsoon. Collision theory explains why. Particles must collide, and only collisions with enough energy (the threshold energy) produce new substances. Five factors change the speed: the nature of the reactants, concentration, surface area, temperature and catalysts. Enzymes in your own saliva are catalysts too. This self-study guide starts from the basics and explains every idea step by step with animations and virtual labs. It answers every textbook question and ends with a revision sheet and a model test.
The chapter in one picture
Reactant particles must collide. Only collisions with at least the threshold energy (ത്രെഷോൾഡ് എനർജി) are effective collisions (ഫലവത്തായ കൂട്ടിമുട്ടലുകൾ) that form products. Heating gives the particles more kinetic energy (ഗതികോർജം), so more of them pass the bar. This is collision theory (കൊളിഷൻ സിദ്ധാന്തം, page 6). Part 3 is a go further idea: a catalyst (ഉൽപ്രേരകം) offers an easier path, as if the bar were lower (page 8). The numbers on the counters change from run to run; compare the three parts.
The chapter at a glance
🧩 Four kinds of reactions
- Combination (സംയോജന രാസപ്രവർത്തനം): A + B → AB · CaO + H₂O → Ca(OH)₂
- Decomposition (വിഘടന രാസപ്രവർത്തനം): AB → A + B · CaCO₃ → CaO + CO₂↑
- Double decomposition (ദ്വിവിഘടന രാസപ്രവർത്തനം): AB + CD → AD + CB · NaCl + AgNO₃ → AgCl↓ + NaNO₃
- Displacement (ആദേശ രാസപ്രവർത്തനം): A + BC → AC + B · Zn + 2HCl → ZnCl₂ + H₂↑
⏱ Five things that change the rate
- Nature of the reactants (അഭികാരകങ്ങളുടെ സ്വഭാവം): Mg > Zn > Cu with dilute acid
- Concentration (ഗാഢത): more particles per unit volume
- Surface area (പ്രതലപരപ്പളവ്): powder reacts faster than a lump
- Temperature (താപനില): more particles reach the threshold energy
- Catalyst (ഉൽപ്രേരകം): speeds up a reaction and is not used up (MnO₂, enzymes)
How to use this guide
🎬 Watch the animations
Particles collide in a box, atoms change partners, sugar chars, marble fizzes and hydrogen peroxide bubbles, one step at a time. Press Next ▶ or ▶▶ Auto play. Animations pause by themselves when you scroll away; click a lab to start its clock again.
🧪 Use the virtual labs
A change sorter, a particle box with temperature and concentration sliders, a signs-of-change bench, a reaction-type machine, a collision simulator, metal races, lump-versus-powder and warm-versus-cold labs, a catalyst lab and a gas-syringe grapher. The dangerous experiments are shown as safe virtual demonstrations.
✍️ Try before you see
Every textbook table is a fill-in table with a check button, and every question hides its answer behind a button. Work it out in your notebook first. The “Check yourself” quizzes at the end of each page tell you at once whether you are right.
📖 Textbook words
Purple മലയാളം words are the exact terms used in your textbook (pages 95–112), so you can match this guide with your book and write answers in either language.
🔇 Quiet and offline
The pages make no sound and need no internet. Optional “Explore online” boxes link to checked websites (no videos); they open only if you click them. Every page is a single file, so the whole guide works on a computer or phone with no connection.
Learning path
Follow the pages in order. If you already know physical and chemical changes, balanced equations and the idea that particles are always moving, you can skim pages 1–2. Still try their quizzes, because the chapter uses these ideas on every page.
Quick glossary (Malayalam ↔ English)
| Textbook term | English | Meaning |
|---|---|---|
| രാസഗതികം | Chemical kinetics | The study of how fast chemical reactions go and what changes their speed |
| ഭൗതികമാറ്റം · രാസമാറ്റം | Physical change · chemical change | No new substance forms (ice melting) · one or more new substances form (milk turning into curd) |
| രാസപ്രവർത്തനം · രാസസമവാക്യം | Chemical reaction · chemical equation | A process that makes new substances · the reaction written with symbols and formulae |
| നിറവ്യത്യാസം · ഗന്ധം · വാതകം | Colour change · smell · gas | Three signs that a chemical change has taken place |
| അവക്ഷിപ്തം · അവക്ഷിപ്തപ്പെടുക | Precipitate · precipitation | An insoluble solid that forms in a solution (shown with ↓) · the forming of such a solid |
| നീറ്റുകക്ക | Quicklime (CaO) | Calcium oxide; it reacts with water and the beaker becomes hot |
| താപമോചക പ്രവർത്തനം | Exothermic reaction | A reaction that gives out heat |
| സംയോജന രാസപ്രവർത്തനം | Combination reaction | Two or more simple substances combine to form one new compound |
| വിഘടന രാസപ്രവർത്തനം · താപീയ വിഘടനം | Decomposition reaction · thermal decomposition | One compound breaks into two or more substances · breaking down by heating |
| ദ്വിവിഘടന രാസപ്രവർത്തനം | Double decomposition reaction | Two compounds exchange ions to form two new compounds |
| അവക്ഷിപ്തരൂപീകരണ രാസപ്രവർത്തനങ്ങൾ · വാതകരൂപീകരണ രാസപ്രവർത്തനങ്ങൾ | Precipitation reactions · gas-forming reactions | Double decompositions that give a precipitate · that give a gas |
| നിർവീരീകരണം | Neutralisation | An acid and an alkali react to form a salt and water (HCl + NaOH → NaCl + H₂O) |
| ആദേശ രാസപ്രവർത്തനം · തെർമൈറ്റ് | Displacement reaction · thermite | One element replaces another element in a compound · the Fe₂O₃ + Al reaction used to weld rails |
| രാസപ്രവർത്തനവേഗം | Rate of reaction | How fast reactants are used up or products are formed |
| സ്ഫോടനം · തുരുമ്പിക്കൽ | Explosion · rusting | A very fast reaction · a slow reaction of iron with oxygen and water |
| പ്രിസർവേറ്റീവുകൾ | Preservatives | Substances added to food to slow down the reactions that spoil it |
| കൊളിഷൻ സിദ്ധാന്തം | Collision theory | Reactions happen when reactant particles collide with enough energy |
| ഫലവത്തായ കൂട്ടിമുട്ടലുകൾ | Effective collisions | Collisions that have enough energy to form products |
| ത്രെഷോൾഡ് എനർജി · ഗതികോർജം | Threshold energy · kinetic energy | The minimum kinetic energy reactant particles need to form products · the energy a particle has because it moves |
| അഭികാരകങ്ങളുടെ സ്വഭാവം · രൂപാന്തരങ്ങൾ | Nature of reactants · allotropes | What the reacting substances are (sodium or magnesium) · different forms of one element (white and red phosphorus) |
| ഗാഢത · ഗാഢ · നേർപ്പിച്ച | Concentration · concentrated · dilute | The number of particles in a unit volume (യൂണിറ്റ് വ്യാപ്തം) · many particles per unit volume · few |
| പ്രതലപരപ്പളവ് · ഭൗതികാവസ്ഥ | Surface area · physical state | The total area of the outside of a solid · solid, liquid or gas |
| താപനില | Temperature | How hot or cold something is; a higher temperature means faster particles |
| ഉൽപ്രേരകം · ഉൽപ്രേരണം | Catalyst · catalysis | A substance that increases the rate of a reaction without itself undergoing a permanent chemical change · the action of a catalyst |
| എൻസൈമുകൾ | Enzymes | Catalysts made by living things (amylase in saliva changes starch into maltose) |
| ഹേബർ പ്രക്രിയ · സമ്പർക്ക പ്രക്രിയ | Haber process · contact process | Making ammonia with an iron catalyst · making sulphur trioxide (for sulphuric acid) with a V₂O₅ catalyst |
| ഉഭയദിശാ പ്രവർത്തനങ്ങൾ | Reversible reactions (⇌) | Reactions that go both ways: products can change back into reactants |
🌐 Explore online (optional)
Want to go further? The teaching pages end with a few checked websites and simulations (no videos), and page 11 has the full resources hub. They need the internet; the guide itself works offline. To begin, read what chemists mean by the rate of a reaction, or try a simulation of colliding particles:
- 📄 Bombardier beetle Wikipedia
A beetle that defends itself with a catalysed hot spray. - 📄 Reaction rate Wikipedia
How fast reactants turn into products, and what changes it. - 📄 Chemical kinetics Wikipedia
The branch of chemistry that studies reaction rates. - 🧪 Reactions & Rates (PhET simulation) PhET, University of Colorado Boulder
Change temperature and concentration and watch the molecules collide. - 📄 Food preservation Wikipedia
Salting, refrigeration and preservatives slow down spoiling reactions.
Made for self-learning. Works offline – every page is a single file; only the optional "Explore online" links need the internet. Study material prepared by Claude for Madhu's family study folder, October 2026.