Topic 5: Chemical Energetics Flashcards
Tell me about endothermic reactions.
The system absorbs energy.
Causes the temperature of the surroundings to decrease
More energy is needed to break bonds than is released by the formation of new bonds
Give examples of endothermic reactions.
Electrolysis
Thermal Decomposition
Sugar production in photosynthesis
Tell me about exothermic reactions.
The system releases energy
Temperature of the surroundings increases
More energy is released by the formation of new bonds than is required to break bonds.
Give examples of exothermic reactions
Burning
Neutralisation
Acid and metal reactions
Rusting
Draw the energy level diagram for exothermic reactions.
Draw the energy level diagram for endothermic reactions
What is enthalpy change?
The energy stored in the bonds is called the enthalpy.
The change in energy going from reactants to products is called the enthalpy change of the reaction.
What is activation energy?
The minimum amount of energy required for the colliding particles in the reaction mixture to form products.
Tell me about bond breaking and bond forming.
Bond breaking is an endothermic process because it requires energy.
Bond forming is an exothermic process because it releases energy.
How do you calculate change in energy?
Energy in - energy out = change in energy.
What does negative energy change show?
exothermic reaction
What does positive energy change show?
Endothermic reaction.
