Types of Chemical Reactions
Combination Reaction
A single product is formed from two or more reactants, is called Combination Reaction.
2Mg +O2→2MgO
Decomposition Reaction
A single reactant breaks down to yield two or more products , is calledDecomposition Reaction.
(a) Thermal decomposition 2Pb(NO3)2 → 2PbO + 4NO2 +O2 (b) Electrolysis 2H2O →2H2 +O2 (c) Photo chemical reaction 2AgBr →2Ag +Br2
Displacement Reaction
One element is displaced by another element , is called Displacement Reaction.
Zn + CuSO4→ ZnSO4 + Cu
Double displacement reaction
Exchange of ions between reactants , is called Double displacement reaction.
AgNO3 +NaCl →AgCl +NaNO3
Redox reaction
Both oxidation and reduction take place simultaneously, is called Redox reaction.
CuO + H2 → Cu + H2O
Exothermic reaction –
A chemical reaction in which heat energy is evolved, is called Exothermic reaction.
C + O2 →CO2 (g) + heat
Endothermic reaction-
A chemical reaction in which heat energy is absorbed , is called Endothermic reaction.
ZnCO3 + Heat →ZnO + CO2
Redox reaction-
Chemical reaction in which both oxidation and reduction take place simultaneously , is called Redox reaction. ZnO + C →Zn + CO
Oxidation-
Reaction that involves the gain of oxygen or loss of hydrogen is called Oxidation.
Reduction –
Reaction that shows the loss of oxygen or gain of hydrogen , is called Reduction.
Effects of oxidation reactions in our daily life – Corrosion , Rancidity
Preventive methods :- (a) Adding antioxidants to the food materials. (b) Storing food in air tight container (c) Flushing out air with nitrogen gas. (d) Refrigeration.