exothermic and endothermic reactions

endothermic reaction pathway diagram

exothermic reaction pathway diagram

in endothermic reactions

• thermal energy is taken during a reaction

• energy is taken in from the surrounding

• more energy is absorbed than released

• temperature of the surrounding decreases

• thermal decomposition and electrolysis

• energy of the products will be higher than the energy of the reactants

• overall energy change is positive

endothermic → entering

in exothermic reactions

• thermal energy is given out during a reaction

• energy is given out to the surroundings

• more energy is released than absorbed

• temperature of the surroundings increase

• combustion and neutralisation reactions

• the energy of the products will be lower than the energy of the reactants

• overall energy change is negative

exothermic → exiting

activation energy E_a 

the minimum amount of energy colliding particles must have to react

enthalpy change ΔH

refers to the transfer of thermal energy during a reaction

exothermic reactions - enthalpy is negative

endothermic reaction - enthalpy is positive

reaction

to have a product formed, particles need to collide with activation energy which allows a reaction to occur and form a product

bond breaking

endothermic reaction

bond making

exothermic reaction

energy change formula