C7 - Energy Changes (GCSE only) Flashcards
what is an exothermic reaction
transfers energy to the surrounding and the temperature increases
what is an endothermic reaction
takes in energy from its surroundings and the temperature goes down
examples of using energy transfer
- hot packs (to warm you up)
- cold packs
- self heating cans
what is a reaction profile
a diagram showing how the energy changed in a reaction
what is the activation energy
the mimimum amount of energy required before a collision will result in a reaction
what is bond energy
the enrgy required to break a bond or the energy released when a bond is formed
in terms of bond breaking and making what is an exothermic reaction
less energy is required to break the bonds than is
released when making the bonds
In terms of bond breaking and making, what is an
endothermic reaction?
more energy is required to break the bonds than is
released when making the bonds
what is a rate
a measure of the change per unit time (per second) we can calculate rate using the formula
rate = amount of reactant used or product formed / time
what are examples of an endothermic reaction
- thermal
decomposition - citric acid and
sodium hydrogen
carbonate
what are examples of an exothermic reaction
- oxidation
- combustion
- neutralisation
how are bonds broken
if bonds are broken it means that a bond requires energy to break so the reaction in endothermic
how are bonds formed
if bonds are formed, an energy is released to create bonds meaning the reaction is exothermic
