Exo and Endothermic Reactions Flashcards
exothermic reactions…?
transfer energy to the surroundings (give out energy)
give out heat energy
- KJ
examples of exothermic reactions
burning
neutralisation
magnesium + water
endothermic reactions
take in heat energy from the surroundings
+ KJ
examples of endothermic reactions
electrolysis
thermal decomposition
cracking
in an exothermic reaction, products have ______ energy that the reactants
less
heat is released
in an endothermic reaction, the products have _____ energy than the reactants
more
heat is absorbed
what needs to happen for a reaction to occur?
two or more molecules must collide with sufficent energy. this energy is called activation energy
a catalyst ….?
a catalyst is a substance which speeds up a reaction by lowering the activation energy without being used up in the process
it offers and alternative reaction pathway with lower activation energy
energy must be ______ to break bonds.
supplied. therefore this is an endothermic reaction
energy must be ______ when new bonds are formed.
released. this means this is an exothermic reaction.
what is activation energy?
the minimum amount of energy required for a reaction to occur
why does increasing the temperature increase the rate of reaction?
particles have greater kinetic energy
collisions occur more frequently
particle collisions are harder because particles have more speed, so there are more successful collisions
why does increasing concentration increase the rate of reaction?
- more particles in the same volume so collisions occur more frequently (more successful collisions)
effect of surface area on rate of reaction?
more collisions between reactants as there is a greater area for collisions to occur over
