Rate Equations Flashcards
(43 cards)
definition of rate of reaction
The change in concentration per unit of time
Definition of activation energy
The minimum energy required for a reaction to occur
Why does a higher temperature increase the rate of reaction
A higher temp more particles have E>Ea
Greater frequency of successful collisions
Why does a higher concentration/pressure increase the rate of reaction
more particles in a small amount of space
so more collisions between particles
so more frequent successful collisions
Why does breaking a solid into smaller particles increase the rate
increased surface area
more collisions between particles
greater frequency of successful collisions
What is a catalyst
a substance which increases rate of reaction
without being used up
How does a catalyst work
provides a reaction ruite
what is the x axis on a maxwell-boltzmann distribution curve
energy of particles
what is the y axis on a maxwell-boltzmann distribution curve
Number of particles
What does the area to the right of the Ea represent
particles which have enough energy to react
Why do the majority if chemical reactions start off with a fast rate of reaction and then slow down before it stops
initially, there is a high concentration of reactants so a large frequency of successful collisions
as reactants get used up, successful collisions become less frequent
once one or more reactants are used up, zero successful collisions
what does the gradient on a concentration vs time graph tell you
the rate of reaction at that specific moment in time
how to calculate the gradient
change in y / change in x
Rate α [X][Y]
equal effect on rate.
Rate α [X][Y]²
Y has greater effect on the rate
what is α the same as
k=
what is ‘k’
rate constant
What should units of k always end in and why
s-1 as it doesnt cancel out with anything
What order are these?
Rate = k[X][Y]²
[X] - first order
[Y]² - second order
What does zero order mean
Changing concentration of the reactant has no effect on the rate of reaction
What does first order mean
Rate is directionally proportional to the concentration.
eg. doubling the concentration doubles the rate
what does second order mean
Rate is proportionally to the square of the change in concentration
eg. doubling the concentration causes the rate to increase by 4 (2²)
What is the only thing that affects k
temperature
What does it mean when the rate vc conc graph is a horizontal line
zero order
