Topic 6- The Rate and extent of Chemical Change Flashcards
what does the rate of a chemical reaction depend on?
The collision frequency of reacting particles (how often they collide). More collisions= faster reaction
the energy transferred during a collision. Particles have to collide with enough energy for it to be successful
what factors affect the rate of reaction?
temperature
the concentration of a solution/pressure of a gas
surface area- changes depending on size of lumps of solid
presence of a catalyst
what does more collision increase
the rate of reaction
how does increasing the temperature increase the rate of reaction
increased temp = particles move faster
therefore they collide more frequently
faster = more energy = more of collisions will have enough energy to make the reaction happen
how does increasing the conc increase the rate of reaction
more concentrated = more particles are moving in the same volume of water
therefore collisions between the reactant particles are more frequent
how does increasing the pressure increase the rate of reaction
more pressure = same number of particles occupy a smaller space
therefore collisions between the reactant particles are more frequent
how does increasing the SA increase the rate of reaction
if one of the reactants is a solid then breaking it up increases its SA to Volume ratio.
this means for the same volume of the solid, the particles around it will have more area to work on
therefore more frequent collisions
how does using a catalyst increase the ROR
catalyst decreases the activation energy by providing an alternative reaction pathway with a lower activation energy
enzymes are biological catalysts
how is equilibrium reached
when the reactants react their concentrations will fall so the forwards reaction will slow down
BUT as more and more products are made and their concs rise, the backward reaction will speed up
after a while the reactions will both be going at he same rate = EQUILIBRIUM
what’s a dynamic equilibrium
when both reactions are still happening but there’s no overall effect.
this means that the concs of reactant and products have reached a balance and won’t change
where does equilibrium take place
in a closed system
what is a closed system
none of the reactants or products can escape and nothing else can enter/get in
if the equilibrium lies to the right, it means that…
the concentration of products is greater than that of the reactants
if the equilibrium lies to the left, it means that…
the conc of reactants is greater than the conc of products
what does the position of equilibrium depend on
temperature
pressure (only gases)
conc of reactants and products
