C7 Flashcards
Exothermic reaction ?
reaction that gives out heat
2 examples of exothermic reactions ?
self heating cans
hand warmers
2 uses of exothermic reactions
combustions
neutralisation
endothermic ?
takes in heat energy - surrounding get colder
example of an endothermic reaction
sports injury pack
Experiment of measuring the energy released from a chemical reaction
polysterine cup
insulated lid
thermometer
mixed chemicals
the required practicals steps
25cm3 of the chemical
check temperature
add 2nd chemical nd stir
check temperature again
main errors made in the practical ?
how can this be reduced ?
why is the mixture stirred ?
some energy gets to escape
insulate the beaker + put lid on
to make sure its got even heating (no cold spots)
activation energy ?
energy needed to start a chemical reaction
reaction profile for exo
reactant starts higher drops down to product
reaction profile for endo
reactants starts low nd raised then drops a little to the product
bond breaking and making
more energy is released when the new bonds are formed than is put in to break the old bonds
for endo reactions bond breaking
more energy is put into break the old ones
