Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

Exothermic reactions

•Download as PPTX, PDF•
•
A Cry For Help
A Cry For Help

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 of 9
Exothermic Reactions Presented By- Soumya Vishwakarma
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
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.
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
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.
• 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]
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}
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 :
Made By- SoumyaVishwakarma Chemistry Creative- FA1

More Related Content

Exothermic reactions

  • 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 :