Energy changes Flashcards
What is an exothermic reaction
Energy is transferred from the chemicals to the surrounding. Exothermic changes are shown as negative
Combustion is an example of exothermic reaction
what is an endothermic reaction
Energy is gained from the surroundings. changes are seen as positive
Reaction profile for Exothermic reaction
The difference in height represents the overall energy change in the reaction per mole.
The intial rise in energy represents the energy needed to start the reaction.(activation energy)
Reaction profile for endothermic
Products are at a higher energy than the reactants
Difference in height represents the overall energy change during the reaction
Bond breaking
During a chemical reaction Old bonds are broken and new bonds are formed
energy must be supplied to break existing bonds so bonds breaking is endothermic and bond forming is exothermic
In exothermic the energy released by forming bonds is greater than the energy used to break them
In e do thermocouple the energy used to break bonds is greater than the energy released by forming them
What is activation energy
The minimum amount of energy that particles must have in order to react
Bond energies
Breaking bonds= endothermic (p)
Making bonds= exothermic (n)
Reactants break bonds
Products make bonds
What is a use of exothermic reactions
Hand warmers
Self heating cans
Combustion
Wha is an example of an endothermic reaction
Thermal decomposition
