Kinetics Flashcards
What is the equation used to calculate the rate of
reaction?
Amount of product used or product formed / time
What does collision theory state?
For a reaction to take place particles must collide, in the correct orientation and with enough energy to break the bonds in the reactants
Explain why increasing the temperature speeds up a reaction
It gives the particles more energy so they collide more often and the collisions have more energy
Explain why increasing the concentration of a
solution speeds up a reaction
It means there are more particles present so it will increase the number of collisions
Explain why increasing the pressure on reactions involving gases speeds up the rate of reaction
Increasing the pressure increases the number of gas
particles present in a certain volume
This increases the number collisions between reacting
particles, which increases the rate of reaction
Explain how breaking up a solid reactant increases
the rate of reaction.
Breaking up a solid, increases the surface area
This means that there is a greater area of solid exposed for other particles to collide with.
This increases the likelihood of a successful collisions and therefore speeds up the reaction
What is activation energy?
The minimum amount of energy required to break the bonds in the reactants to allow the reaction to occur
What is along the x and y axes on a maxwell-Boltzmann distribution curve?
X - energy
Y - number of particles with energy
Why does the Maxwell Boltzmann curve start at the
origin?
No particles have zero energy
Why does the right-hand side of the curve never
touch the axis at zero?
There is no upper limit to the amount of energy some particles may have
What does the area under a Maxwell Boltzmann
curve correlate to?
The trial number of particles
What does the area under a Maxwell Boltzmann
curve at and above Ea represent?
The number of particles that have at least the activation energy and above to react
What happens to the number of particles with Ea
and above at higher temperatures?
Increases
What are catalysts?
Catalysts are substances that affect the rate of chemical reactions without being chemically changed themselves.
How does a catalyst increase rate of reaction?
Catalysts provide an alternative pathway with a
lower activation energy, This means more particles have the minimum energy for successful collisions to occur
What is a heterogenous catalyst?
A catalyst that is in a different phase to the reactants
What is a homogenous catalyst?
A catalyst that is in a different phase to the reactants
What two reactions take place on the surface of a heterogenous metal catalyst?
- The reactants (usually gases) form weak bonds with the metal atoms of the catalyst (a process called adsorption) that hold the reactants in the right
- position for them to react together on the catalyst’s surface The products then break away from the metal atoms (process is called desorption) which frees up room on the catalyst surface for more gases to take their place and react
