Exothermic and Endothermic Reactions

- What is Exothermic and Endothermic Reactions ? Exothermic reactions : Reactions accompanied with producing heat Reactants Products + Heat Where, Heat content of reactants is more than heat content of products Δ H = H Products - H Reactants = Negative value

- What is Exothermic and Endothermic Reactions ? Endothermic reactions : Reactions accompanied with absorbing heat Reactants + Heat Products Where, Heat content of reactants is less than heat content of products Δ H = H Products - H Reactants = Positive value

Examples : Look to the following reaction, C + O 2 CO 2 + Energy What is the type of reaction ? Why ? Exothermic Because it produce energy ( heat )

Examples : Look to the following reaction, CaCO 3 + Energy CaO + CO 2 What is the type of reaction ? Why ? Endothermic Because it absorp energy ( heat )

Examples : Look to the following reaction, K + H 2 O KOH + H KJ What is the type of reaction ? Why ? Exothermic Because it produces energy ( heat ) equals to 184 kj

Examples : Look to the following reaction, H 2 + I 2 2HI, ΔH = KJ What is the type of reaction ? Why ? Endothermic Because it has positive ΔH

Examples : Look to the following reaction, H 2 + O 2 H 2 O, ΔH = KJ What is the type of reaction ? Why ? Exothermic Because it has negative ΔH

- What is activation energy? The minimum energy required by molecules to react on collision. ΔH is the change in energy ( Enthalpy change ) ΔH = H products - H reactants

- In exothermic reaction, Reactants Products Energy ΔH Reaction ΔH = H products - H reactants ΔH = negative value

- In endothermic reaction, Reactants Products Energy ΔH Reaction ΔH = H products - H reactants ΔH = positive value