Rate Equations Flashcards
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
What does it mean when the rate vc conc graph is a straight diagonal line
1st order
What does it mean when the rate vc conc graph is a line curving up
2nd order
What is the Arrhenius equation
k=Ae^−Ea/RT
What is K in the Arrhenius equation
Rate constant
What is A in the Arrhenius equation
Arrhenius constant
What is e in the Arrhenius equation
e on the calculator
What is Ea in the Arrhenius equation
Activation energy
What is R in the Arrhenius equation
gas constant (8.31)
What is T in the Arrhenius equation
Temp in kelvin (+273)
rearrangement of Arrhenius equation
ln(k)= ln A - Ea/RT
what happens to the rate of reaction when you increase the temperature
the higher the temperature the faster the rate of reaction
why is the higher the temperature the faster the rate of reaction becomes
the more kinetic energy each particle has
a greater proportion of particles has E>Ea
so greater frequency of successful collisions
how can you use equation of a straight line with the Arrhenius equation
y = mx+c
Ln (k)= -Ea/RT + Ln A
When using the equation of a straight line with the Arrhenius equation
what is y
Ln K
When using the equation of a straight line with the Arrhenius equation
what is x
1/t
When using the equation of a straight line with the Arrhenius equation
what is m
-Ea/R
When using the equation of a straight line with the Arrhenius equation
what is c
Ln A
what is m in the equation of a straight line
gradient
what is c in the equation of a straight line
the height at which the line crosses the y -axis
