9 Flashcards
what is the equation for rate of reaction
rate of reaction = change in conc/ change in time
how do you calculate rate of reaction from a concentration time graph
the gradient of the line = the rate of reaction
what are the requirements for reactions to occur
molecules must collide with sufficient energy in the correct orientation
what is a steric factor
when the shape of a molecule influences reactions
define activation energy
the minimum energy that colliding particles must have in order for a reaction to occur
how does concentration effect rate of reaction
increased concentration:
higher frequency of collisions because the particles are closer together
how does pressure effect rate of reaction
increased pressure:
higher frequency of collisions in gas phase reactions
how does surface area effect rate of reaction
increased surface area:
only effects rate of reaction in heterolytic reactions involving a solid
gives more surfaces for the reaction to occur on
how does an increase in temperature effect rate of reaction
increased fraction of molecules which have the required activation energy
higher kinetic energy leads to a higher frequency of collisions
why does a reaction in solution have a higher rate of reaction than the same reaction in gas phase
solute molecules are trapped in solvent cages therefor many solute molecules can be trapped together so they all react more rapidly
define catalyst
a substance that increases the rate of reaction but is chemically unchanged at the end of the reaction
state 2 economic advantages of catalysts
increase rate of chemical reaction so more of the desired product can be made in a given time period
reactions can be done at a lower temperature so energy costs are decreased
what is a heterogenous catalyst
one that is in a different phase to that of the reactants
