Question

Explain me about every types of reaction with help of examples

Answer 1

1. Combination Reactions:-------

• Is also referred to as a synthesis reaction
• It is a chemical change in which two or more substances react to form a new singular substance
• The product is a compound in this form of reaction
• You can tell this reaction has occurred because on the reactant side there are multiple substances, while on the product side there is only one product

eg:-2 H2 + O2----->2H20

​2) Decomposition: A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:
AB ---> A + B
This type of reaction is easily identifiable, because: • It is the exact opposite of synthesis; if you know one you know them both
• There is always one reactant. If you see one reactant that’s a compound and several products, a decomposition reaction occurred.
One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:
2 H2O ---> 2 H2 + O2

3) Single displacement: This is when one element trades places with another element in a compound. These reactions come in the general form of:
A + BC ---> AC + B

• It is identifiable by its symmetry. On the reactant side there is a single element and a compound, as there is on the product side.

• No reaction will occur if the most reactive element is already in the compound
One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:
Mg + 2 H2O ---> Mg(OH)2 + H2

4) Double displacement: This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:
AB + CD ---> AD + CB

• Generally take place in aqueous solution
• • Often produce a precipitate, a gas, or a molecular compound (i.e. water)

One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:
Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3

5)Oxidation → When a substance gains oxygen or looses hydrogen.
Oxidation in everyday life. eg:-Cu + O2--->2CuO

1. Corrosion – When a metal is oxidised by action of air and moisture [that’s why metals are coated]
2. Rancidity – When fats and oils are oxidised, their smell and taste change [that’s why food is kept in air-tight containers]

Reduction → When one substance loses oxygen or gains hydrogen​
EG:-- CuO + H2---->Cu+ H2O


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