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chemical reactions - Coggle Diagram

- - - - ↓
  - - - When a reaction is characterized by release of energy, it is called exothermic reaction.
        
        heat is evolved
        
        it causes rise in temperature
    - - When a reaction is characterized by absorption of energy, it is called endothermic reaction.
        
        heat is absorbed
        
        it causes fall in temperature
  - - - ↑
- - - - A +BC -----------> AC +B
        
        Displacement reaction are also called as substitution reactions.
        
        Reactivity series of metals
        
        The arrangement of metals in a vertical column in the decreasing order of their reactivity is called the reactivity series of metals
        
        potassium in most reactive and gold is least reactive
        
        table
  - - - AB +CD -----> AD+CB
        
        it is of two types
        
        Neutralisation reaction
        
        The reaction in which an acid and a base react forming salt and water is called neutralisation reaction
        
        Activity 5 pg no 81
        
        Precipitation reaction
        
        In this type of reaction one of the product is precipitated.
  - - - AB ----> A+B
        
        Activity 4 pg no77
  - - - A+B ----> AB
        
        These reaction r called as combination and synthesis reactions.
        
        Activity 3 , pg no 75
- - - - The representation of a chemical reaction using symbols and formulae for the reactants and products is known as chemical equation.
        
        reactants- left ; products- rights ; two or more reactants +; reactants --------> products.
  - - - It does not tell about the conditions of temperature, pressure etc.
        ( it is therefore required to write the conditions above or below the arrow)
        
        It does not give the speed of the reaction.
        
        It does not indicate the states of substances .
        ( it is therefore required to write the states in brackets)
  - - - Thus a chemical equation is complete when it is balanced.
        
        Chemical bond is the attractive force that holds groups of atoms of a molecule together.
        
        How are new substances formed?
        
        ans) During chemical reaction the chemical bond between the atoms or group of atoms of reacting substances break and rearranges to form new bond, thus making new substance.