2.2 rates of reaction Flashcards
what are the factors that affect rate of reaction?
concentration of a solution (pressure of a gas), surface area of a solid, temperature, catalyst, light (in some reactions).
why is the rate fastest at the start of a reaction?
the concentration of reactants is at their highest.
what happens when the rate is zero?
the reaction stops; one of the reactants has been used up.
what is collision theory?
for a reaction to take place, particles must collide efficiently. the greater the number of collisions, the higher the chance that they will be successful.
what is activation energy?
the minimum energy needed for particles to collide successfully.
how does increasing concentration affect rate of reaction?
there are more particles in a given volume, so distance between the particles are reduced and there is an increase in the number of collisions.
how does increasing temperature affect rate of reaction?
at higher temperatures, particles have more kinetic energy and move faster, increasing the number of collisions.
how do catalysts affect rate of reaction?
catalysts provide a different reaction pathway to increase rate and do not get used up in the reaction. the rate increases as the new pathway has a lower activation energy.
what is a homogeneous catalyst?
the catalyst is in the same state as the reactants. they take an active part in the reaction rather than being an inactive spectator.
what is a heterogeneous catalyst?
the catalyst is in a different state than the reactants.
why are heterogeneous catalysts usually d-block transition metals?
the metal provides a reaction site for the reaction to take place. gases are absorbed on the metal surface and react and the products desorb from the surface.
how is change in gas volume measured?
the volume of the gas can be recorded using a gas syringe at various times.
how is change in gas pressure measured?
the change in pressure (at constant volume) can be followed using a manometer.
how is change in mass measured?
the change in mass at various times can be followed using a weighing balance.
