When two or more substances chemically bonded together to produce a single product, it is called as combination reaction or synthesis reaction. When the bond forms between the elements, heat is released; this is because the reactions are usually exothermic.
1. Reaction between two elements
Ex: C + O2`->` CO2
Here the carbon is completely burnt in oxygen which results in carbon dioxide
2. Reaction between two compounds
Ex: CaO + H2O `->` Ca ( OH)2
Here the calcium oxide (lime) combined with water gives calcium hydroxide which also known as slaked lime.
3. Reaction between an element and compound
Ex: O + H2O `->` H2O2
Here oxygen which is an element combined with water which is a compound gives hydrogen peroxide.
1. Na2 + H2O `->` 2NaOH
Here sodium oxide is combined with water gives sodium hydroxide.
2. 4Li + O2 `->` 2Li2O
Here lithium is combined with oxygen to form lithium oxide.
3. 2Mg + O2 `->` 2 MgO
Here magnesium is combined with oxygen to form magnesium oxide.
4. H2 + Cl2 `->` 2 HCL
Here hydrogen is combined with chlorine to form hydrochloride.
5. NH3 + HCl `->` NH4Cl
Here colorless ammonia is added to colorless hydrogen chloride gives ammonia chloride.
6. 2H2 + O2 `->` 2 H2O
Here hydrogen is burned in the air or oxygen produces water.
7. S + O2 `->` SO2
Here sulphur is burned in the air to produce sulphur dioxide.
8. Ba + F2 `->` Ba F2
Here barium metal and fluorine gas is combined to produce salt barium fluoride which is highly exothermic reaction.
9. MgO + CO2 `->` MgCO3
Here magnesium oxide is combined with carbon to produce magnesium carbon dioxide.
10. 2Al + 3Br `->` 2AlBr3
Here aluminum is combined with bromine which produces 3 + aluminum iron and 1+bromine iron.
Forthcoming post is on the topic Reaction Rate Equation keep reading my blogs.
Chemical reactions are of the following six types:
1)Combustion reaction: It is a type of reaction in which oxygen combines with the other compound and forms carbon dioxide (CO2) and water (H20)
Ex: C10H8 + 12 O2 -----------> 10 CO2 + 4 H2O
CH4 + 2 O2 ---------------> CO2 + 2 H2O
2)Synthesis Reaction: It is a type of chemical reaction in which two or more simple substances combine to form one single complex substance.
Ex: C + O2 ----------> CO2
CaO + H2O -----------> Ca(OH)2
3) Decomposition Reaction: It is a type of chemical reaction in which a complex substance breaks down to simpler substances.It is opposite of synthesis reaction.
Ex: 2 N2O5 ----------> 4 NO2 + H20
2 KClO3 -------------> 2 KCl + 3 O2
4) Single displacement reaction : It is a chemical reaction in which an element displaces another element in a compound .
Ex: Mg + 2 HCl -----------> MgCl2 +H2
Fe2O3 + Zn ------------> Zn2O3 + 2 Fe
5) Double displacement reaction:This is a type of chemical reaction in which the anions and cations in the reactants interchange their positions and form two different compounds.
Ex: 2 NaCl +H2SO4 -------------> Na2SO4 + 2 HCl
AgNO3 + KCl ---------------> AgCl + KNO3
6) Acid - Base reaction: It is a type of double displacement reaction in which acid and base react to form salt and water.
Ex: HCl + NaOH -------------> NaCl + H20
H2SO4 + 2 NaOH ----------> Na2SO4 + 2 H2O
7) Isomerisation : It a type of chemical reaction in which a chemical compound undergoes a structural rearrangement without any change in its net atomic composition.
8) Disproportionation : Its a type of chemical reaction in which a single reactant forms two products with different oxidation states.
Ex: Pb+2 ------------> Pb + Pb +4. here in the products lead has 0 and +4 oxidation states.