sci_chem
Rates of Reaction
Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.
Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.
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Chemistry · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
A fast reaction (like an explosion) finishes in a moment; a slow one (like rusting) takes years. We measure rate as amount changed per unit time.
Most collisions just bounce off. Only a collision with energy above the activation energy and the correct orientation actually reacts.
Each one works by making collisions more frequent or more of them successful. More successful collisions per second means a faster rate.
It speeds the reaction without being used up, so a tiny amount works again and again. Enzymes are biological catalysts.
Hard words & meanings
| rate of reaction | how quickly reactants are used up or products are formed, per unit time |
| collision theory | the idea that particles react only when they collide with enough energy and correct orientation |
| activation energy | the minimum energy a collision must have for a reaction to occur, symbol Ea |
| catalyst | a substance that speeds a reaction by lowering the activation energy and is not used up |
| surface area | the total area of solid exposed to the other reactant; greater for powders |
| concentration | the amount of dissolved substance in a given volume of solution |
| reaction profile | a graph of energy against progress showing reactants, products and the activation energy peak |
| exothermic | a reaction that releases energy, so products have less energy than reactants |
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