Rates Flashcards
What is the rate of reaction
The change in concentration of a reactant or product over a period of time
What is the collision theory
Particles must collide with enough energy and at the correct orientation to react
What is the activation energy
The minimum energy particles need to have to react
Equation for rate
Rate = k [A]^m[B]^m
Square bracket represents concentration
Reaction orders
Zero order - rate is not affected by the reactant
First order - rate is proportional to [A]
Second order - rate is proportional to [A]^2
Total order - adding the individual orders together
How are orders represented on graphs
Zero - straight line going horizontal
First - straight diagonal line
Second - curved line
What is K
K is the rate constant with units of mol-1 dm3 s-1
K=rate/[A][B]
What is the rate determining step
The slowest step or a reaction with multiple steps
The overall rate of reaction is determined by the slowest step
Making the rate determining step the slowest step
Steps which have a zero order reactant can’t be the RDS
Arrhenius’ equation
K = Ae ^ -Ea/RT
K= rate constant
Ae = Arrhenius constant (e)
Ea = activation energy
R = gas constant = 8.31
T = temp in kelvin
Simplified form of Arrhenius’ equation
lnk = -Ea/RT + lnA
Effect of activation energy on K
Increasing Ea, rate decreases as fewer particles have sufficient energy to collide in the correct orientation causing K to decrease
Effect of temperature on K
Increasing temp, increases rate as particles have more kinetic energy so move faster, more successful collisions increasing K
