energetics Flashcards
in terms of energy what happens when a chemical reaction occurs?
energy changes occur, generally in the form of thermal energy
the energy change is either endothermic or exothermic
what is a endothermic reaction?
at energy is absorbed from the surroundings during the reaction
positive enthalpy change
more energy is used to break bonds than is released in making bonds
what is an exothermic reaction?
heat energy is released to the surroundings during the reaction
negative enthalpy change
more energy is released making bonds than used to break bonds
what is activation energy?
the minimum amount of energy required to start a reaction
what is bond strength?
the energy in a covalent bond
a measure of the strength of a chemical bond
how do you calculate enthalpy change of a reaction?
q=mcΔT
m = mass of the solution that changes temperature
c = specific heat capacity (4.2)
ΔH = temperature change
what energy change is breaking bonds associated with?
endothermic reaction
what energy change is making bonds associated with?
exothermic reaction
give 2 examples of exothermic reactions
combustion of fuels
neutralisation
give an example of an endothermic reaction
thermal decomposition
