Chapter 9 Rates of Reaction Flashcards
How to find the rate of reaction in general
What does the rate of reaction depend on
Measure the
amount of reactant used per unit of time
amount of product produced per unit of time
depends on how many successful collisions there are in a given unit time
Charactersitcs about rate of reaction and the graph for it
Rate of reaction is greatest at the start but slowly decreases until the reaction is over
When the reaction is the fastest, the curve is the steepest
When the reaction is over, the curve is flat
How to find the average rate of reaction
Total product produced (hydrogen for eg) / total time for reaction
How to change the rate of reaction
concentration
temperature
surface area of reactant
pressure
adding/removing a catalyst
how does concentration affect the rate of reaction
Relation between concentration and ror
concentration increases the number of particles per unit volume which increases rate of successful collisions.
Directly proportionate
how does temperature affect the rate of reaction
an increase in temp increases ROR in 2 ways:
> more thermal energy - more kinetic energy for particles - move faster so higher rate of collisions
more particles have sufficient activation energy hence there is a higher rate of SUCCESSFUL collisions
direclty proportionate
How much does the rate of reaction increase for an increase of every 10 Celsius
Generally doubles for every 10 celsius
how does surface area of reactant affect the rate of reaction
as surface area of solid reactant increases increases there is more exposed surface which increases the rate of successful collisions
(if powered vs solid reaction will take place faster in powdered state)
Directly proportionate
How does pressure affect the rate of reaction
what state of matter has to be present
For reactions involving Gasses.
When pressure is increased the volume is reduced, therefore the concentration of the gas per unit volume increases which leads to more successful collisions.
Directly proportionate
2 essential factors that must be there for a reaction to take place (collision theory)
Particles must collide together
Collisions must have enough energy for them to be successful
What is a catalyst
A substance that increases the rate of reaction but does not take part in the reaction itself and remains unchanged after the reaction takes place.
What are enzymes
proteins made by cells which act as biological catalysts.
How do catalysts speed up reactions
catalysts reduce activation energy which means that particles now need less energy to react. This increases rate of successful collision
