reaction rates Flashcards
what is meant by the term ‘rate’?
the change of concentration or amount of product produced over time
how do you calculate rate of reaction?
(reactants used / product made) / time
what is collision theory?
particles must collide in the right direction and have the minimum amount of kinetic energy for a reaction to take place
what is ‘activation energy’?
the minimum amount of energy required to break the bonds of the reactants
describe the effect of concentration on rate of reaction?
- increased concentration
- particles are closer together
- more frequent successful collisions
- increased rate of reaction
describe the effect of temperature on rate of reaction?
- increased temperature
- more molecules have more than the activation energy
- particles move around more
- more frequent successful collisions
- increased rate of reaction
describe the effect of pressure on rate of reaction?
- increased pressure
- more particles per unit volume
- more frequent successful collisions
- increased rate of reaction
describe the effect of catalysts on rate of reaction
- provides an alternative pathway for reaction with a lower activation energy
- more particles have the activation energy
- increased rate of reaction
what does it mean if a reaction is exothermic?
reactants have more energy than products
energy is released
what does it mean if a reaction is endothermic?
products have more energy than reactant
energy is taken in
in which direction does the activation energy arrow go on a reaction profile?
from reactants to top of activation curve
in which direction does the enthalpy arrow go on a reaction profile?
from reactants to products
what does the increase in activation energy curve show on a rates graph?
molecular bonds stretch due to an increase in kinetic energy
what does the activation energy curve peak show on a rates graph?
bonds having enough energy to break
describe the energy in endo and exothermic reactions
endothermic = energy is absorbed
exothermic = energy is released
