rates of reaction - effect of temperature, surface area and concentration on rate Flashcards
(16 cards)
what is collision theory
chemical reactions can only take place when the reacting particles collide with each other. the collisions must have sufficient energy
what is the rate of a chemical reaction determined by
the frequency of successful collisions
why are reactions rapid to begin with
there is a large number of reactant molecules meaning there are more successful collisions per second
what does it mean to have a higher concentration
the number of collisions per second will be much higher meaning the rate of reaction will increase
what is the link between rate of reaction and the concentration
the rate of reaction is proportional to the concentration
how does this work with gas
the higher the pressure the higher the amount of successful collision per second
what is the key thing to do with a solid reacting with a liquid or a gas
the particles in a solution or gas only react with the particles on the surface of the solid
why does the rate of reaction increase when we increase the surface area
because there are more particles to collide with meaning more successful collisions per second
smaller sized blocks of reactant have….
a larger surface area to volume ratio
how can we test this theory?
- use marble chips
- add hydrochloric acid to start producing carbon dioxide
- measure the volume of gas and so therefore the rate of reaction
- repeat but change the surface area of marble chips and see how that effects the rate of reaction
how can we get a more accurate result
by using a gas syringe
in a reaction profile, what does it tell us when the products have less energy then the reactants
that the reaction must be exothermic as energy is being released from the reaction to the surroundings
define activation energy
the minimum amount of energy the particles must have in order to react
what does increasing the temperature do
it increases the rate of reaction
why??
increasing the temperature increases the energy of the particles meaning they can move faster and increase the number of collisions
relationship between temperature and rate of reaction
they are proportional
