Energy Changes

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Cards (21)

what is an exothermic reaction
energy is transferred to the surroundings so temperature increases
what is an endothermic reaction
energy is taken in from the surroundings so temperature decreases
give examples of exothermic reactions
combustion
neutralisation
respiration
some oxidation reactions
give everyday uses of exothermic reactions
self heating cans and hand warmers
give examples of endothermic reactions
thermal decomposition
photosynthesis
citric acid
sodium hydrogen carbonate
give everyday uses of endothermic reactions
sports injury packs
what is the energy of the products compared to reactants in an exothermic reaction
less
what is the energy of the products compered to reactants in an endothermic reaction
more
what is activation energy
minimum energy that particles must have for a reaction to occur
draw a reaction profile for an exothermic reaction
draw a reaction profile for an endothermic reaction
what does a catalyst do to the activation energy
lowers it, by providing an alternative path
draw a reaction profile for a reaction with a catalyst
what is needed to break a bond
energy
what type of process is bond breaking (HT only)
endothermic
what is given out when a bond is made
energy
what type of process is bond making (HT only)
exothermic
why is a reaction endothermic overall in terms of bonds breaking and making (HT only)
more energy is taken in during bond breaking than is given out during bond making
why is a reaction exothermic overall in terms of bonds breaking and making (HT only)
more energy is given out during bond making than is taken in during bond breaking
how can you calculate the overall energy change in a reaction (HT only)
sum of bonds broken - sum of bonds made
How does the bond energy change number tell you if a reaction is endothermic or exothermic?
a negative value shows it is exothermic as it has less energy
a positive value shows is endothermic as it has more energy