Topic 5 - Physical Chemistry Flashcards
exothermic reaction
gives off heat to surroundings
reactants have more energy than products
endothermic reaction
takes in heat from surroundings
products have more energy than reactants
activation energy
minimum amount of energy the particles need to collide and react
activation energy on graph
from reactants to peak of curve
breaking bonds
requires energy
endothermic reaction
making bonds
does not require energy
exothermic reaction
bond energy
amount of energy required to breaj one mole of a particular covalent bond
calculating overall energy change
energy required to break bonds - energy released by forming bonds
or
energy of reactants - energy of products
energy change of exothermic reactions
negative
as heat is being released
energy change of endothermic reactions
positive
as energy is taken in
measuring rate of reaction
quantity of products formed / time taken
or
quantity of reactants used / time taken
how does temperature affect rate of reaction?
increased temp = particles have more kinetic energy
= particles collide more frequently
therefore, more successful collisions occur
resulting in a higher rate of reaction
how does concentration affect rate of reaction?
increased concentration = more particles
= particles collide more frequently
therefore, more successful collisions occur
resulting in a higher rate of reaction
how does surface area affect rate of reaction?
increased surface area = particles can collide more frequently
therefore, more successful collisions occur
resulting in a higher rate of reaction
how does a catalyst affect rate of reaction?
catalyst provides alternate pathway with lower activation energy, so rate of reaction is higher
