The document discusses exothermic reactions. It defines an exothermic reaction as a chemical reaction that releases energy in the form of heat or light. When an exothermic reaction occurs, energy is released to the surroundings. Examples of exothermic reactions given include respiration, burning of fuels like coal and natural gas, formation of water and ammonia, and the formation of slaked lime. Daily life examples provided are combustion, photosynthesis, and the formation of table salt. The document also discusses how the amount of heat released can be calculated using enthalpy change values and explains that exothermic reactions have a negative enthalpy change.

1. Exothermic Reactions
Presented By-
Soumya Vishwakarma

2. Contents:
Exothermic Reactions-What are they?
What Happens When an Exothermic Reaction
Occurs?
Examples of Exothermic Reactions
Daily Life Examples of Exothermic Reactions
1
2
5
3
4
6
Amount of Heat Released in Exothermic Reactions
Interesting Exothermic Reactions

3. An exothermic reaction is a chemical reaction that
releases energy in the form of light or heat.
An exothermic reaction is a chemical or physical
reaction that gives out energy to its surroundings.
It is the opposite of an endothermic reaction.
The energy needed for the reaction to occur is less than
the total energy released.

4. A reaction is EXOTHERMIC if a lot of energy is
RELEASED.
Step 1: Energy must be
SUPPLIED to break
chemical bonds
Step 2: Energy is
RELEASED when new
chemical bonds are made

5. Respiration is considered as an
exothermic reaction because in
respiration oxidation of
glucose takes place which
produces large amount of heat
energy.
Evaporation is both endothermic
and exothermic reaction as heat is
provided as well as evolved in the
form of vapours.

6. • C(s)+ O2(g) →CO2(g) [Burning of Coal]
• 3H2 + N2 →2NH3 + Heat [Formation of Ammonia]
• 2H2(g) + O2(g)→H2O(l) [Formation of Water]
• 2SO2 + O2→ 2SO3 + Heat [Formation of Sulphur Trioxide]
• CH4(g) + 2O2(g)→CO2(g)+2H2O(g) [Burning of Natural Gas]
• CaO(s) + H2O(l)→Ca(OH)2(aq) [Formation of Slaked Lime]
• C6H12O6(aq) + 6O2(aq) → 6CO2(aq) + 6H2O(l) + energy [Respiration]

7. In exothermic reactions energy is released and therefore ΔH is
negative. Heat is released by the system due to the reactants of the
reaction having a greater enthalpy than the products.
For example:-
(1) Combustion of methane:
CH4(g) + 2O2(g) ==> CO2(g) + 2H2O(l) {ΔH=-883kJ/mol}
This can also be written as
CH4(g) + 2O2(g) ==> CO2(g)+ 2H2O(l) + 883kJ/mol
This equation tells us that the combustion of methane is exothermic
and releases 883 kilojoules of energy (in the form of heat) for every
mole of methane (CH4). Given this information we can determine how
much heat will evolve if we burn a certain mass of methane.
(2) 2H2(g) + O2(g) → 2H2O(l) , then ∆H = -285 kJ/mol.
(3) Burning graphite (the most stable form of carbon) and then
decomposing CO2 to CO and O2:
C(s) + O2(g) → CO2(g) {∆rH2}

8. Daily Life Examples Of Exothermic
Reactions
1. Combustion
Combustion of Methane - CH4 +2O2 = CO2 + 2H2O
2. Photosynthesis
6CO2 + 12H2O C6H12O6 + 6O2 +6H2O
3. Formation of Salt
Mixture of sodium metal and chlorine gas which
yields table salt.
2Na(s) + Cl2(g)  2NaCl(s) + energy
Since in Exothermic Reactions Heat Energy
EXITS the system ,Therefore some examples
from daily life are :

9. Made By-
SoumyaVishwakarma
Chemistry Creative- FA1