The document discusses combination reactions, which are chemical reactions where two or more substances combine to form a single new substance. It provides several examples of combination reactions, such as magnesium and oxygen combining to form magnesium oxide, sodium and chlorine combining to form sodium chloride when heated, and calcium oxide combining with water to form calcium hydroxide and release heat in an exothermic reaction. The document notes that combination reactions can be exothermic, as seen in the example of calcium oxide and water, and lists other examples of exothermic reactions like respiration and burning natural gas.

1. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction In this simple combination
reaction, magnesium
combines with oxygen to form
magnesium oxide.
2Mg + O2  2MgO
Magnesium ribbon
Magnesium oxide powder
Subtopic ID: 01.03.01

2. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction
Sodium and chlorine combine
on heating to form sodium
Heat chloride.
2 Na + Cl2 2 NaCl
Sodium metal Chlorine gas Sodium chloride
Subtopic ID: 01.03.01

3. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction Sulphur combines with iron on
heating to give iron sulphide.
Fe + S FeS
Iron Iron powder
Sulphur
powder
Mixing iron Iron sulphide powder
and sulphur
Subtopic ID: 01.03.01

4. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction Let us see some more
examples of combination
reaction. Nitrogen combines
with hydrogen and gives
ammonia on heating. Similarly
sulphur combines with oxygen
Heat to form sulphur dioxide.
N2 + 3H2 2NH3
S + O2 SO2
Subtopic ID: 01.03.01

5. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction
Hydrogen and chlorine
combine to form hydrogen
chloride. Though this reaction
appears to be a simple
combination reaction it
actually requires an electric
spark to trigger the reaction.
H2 + Cl2 2HCl
Subtopic ID: 01.03.01

6. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction
Calcium oxide combines with
water and gives calcium
hydroxide. Look at the
solution bubbling like boiling
water. This is due to release of
heat. Hence it is called
exothermic reaction.
CaO(s) + H2O(l) Ca(OH)2(aq) + Heat
Quick lime Slaked lime
Exothermic
Subtopic ID: 01.03.01

7. CBSE - 10 Chemical Reactions and Equations
Chemistry Types of Chemical Reactions
Combination Reaction
Other examples of exothermic
reactions are respiration,
burning of natural gas and
decomposition of vegetable
matter.
Burning of Natural Gas Respiration
Exothermic
Reactions -
Other
Examples
Decomposition of Vegetables
Subtopic ID: 01.03.01