Bond Enthalpy Flashcards
What is the definition of Endothermic reaction?
Reaction in which energy enters the surroundings
What is the definition of Exothermic reaction?
Reaction in which energy leaves the system to surroundings
Examples of Exothermic.
Combustion, neutralisation reaction
Examples of Endothermic.
Thermal decomposition, photosynthesis
What is enthalpy change equation?
Enthalpy of products - Enthalpy of reactants
Draw the reaction profile of Exothermic.
-Products lower than reactants
-AE is from reactants upwards.
-Energy released is from reactants to products
Draw the reaction profile of Endothermic.
-Products are higher than reactants
-AE from reactants to peak
-Energy absorbed is from products to reactants
What is the definition of enthalpy change of combustion?
Enthalpy change for the complete combustion of 1 mole of a substance
What is definition enthalpy change of formation?
-enthalpy change for when one mole of substance is formed
-from one mole of its elements
-under standard conditions
What does Hess’s law state?
The total enthalpy change for a reaction is the same whichever route is taken
For combustion, what way are the arrows pointing?
Away from reactants towards products
For Formation, what way are the arrows pointing?
Towards the reactants and towards the products
What is the equation for enthalpy of oxidation?
ΔH1= ΔH2+ ΔH3
What the equation for enthalpy of formation?
ΔHr= -(ΔH1)+( ΔH2)
define average bond enthalpy
-energy needed to break one mole of bonds
-In a gaseous molecule averaged over a similar compounds
