Chemical Reactions

What this chapter covers

1. Types of Chemical Reactions

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   • Chemical Reaction and Chemical ChangeNew substances from rearranged atoms.
   • Direct CombinationTwo or more reactants form one.
   • Decomposition ReactionOne compound breaks into simpler substances.
   • Simple DisplacementMore reactive element displaces less reactive.
   • Double DecompositionTwo compounds swap their radicals.

2. Acids, Bases and Neutralisation

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   • AcidsSour; hydrogen the only positive radical.
   • BasesMetal oxides or hydroxides; bitter, soapy.
   • IndicatorsColour change shows acid or alkali.
   • SaltNeutral compound from acid and base.
   • Neutralisation ReactionAcid plus base gives salt, water.
   • Neutralisation in Daily LifeAntacids, soil treatment, fire extinguishers.

3. Oxides

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   • Classification of OxidesAcidic, neutral, basic and amphoteric.
   • Acidic OxidesNon-metal oxides forming acids in water.
   • Neutral OxidesNo effect on litmus; CO, NO.
   • Basic OxidesMetal oxides reacting with acids.
   • Amphoteric OxidesShow both acidic and basic character.
   • Polyoxides and Mixed OxidesHigher oxides; mixtures like Fe₃O₄.

4. Characteristics of Chemical Reactions

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   • Energy ChangesActivation energy; exothermic reactions release heat.
   • Rate of ReactionFaster with more energetic collisions.

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