Unit 6 Kinetics Flashcards
Collision theory
Reactant particles must collide with the correct orientation.
Reactant particles must also collide with sufficient energy to overcome the energy barrier for the reaction, which is called the activation energy
Outline one important feature of Maxwell–Boltzmann distribution
the total area beneath the curve is equal to the total number of particles in the sample.
Also, the area under any region of the curve is directly proportional to the number of molecules having a value of kinetic energy in that range.
How does the Maxwell Boltzmann distribution curve change with temp
As the temperature increases, the particles gain kinetic energy and the curve flattens out. The area under each curve is the same because the number of particles is constant, however the most probable value of kinetic energy has increased (the highest point on the curve has moved to the right).
Rate of reaction formula
Rate of reaction=
decrease in reactant concentration / change in time
or Rate=− (Δ[Reactant]) / ΔT
Rate of reaction=increase in product concentration / change in time
How does temperature affect rates of reaction
particles gain kinetic energy and move with higher velocity. This has two effects on reacting particles:
frequency of collisions between reactant particles increases because particles have more kinetic energy at higher temperatures.
higher temperature, a greater proportion of reactant particles will collide with energy equal to or greater than the activation energy for the reaction.
How does concentration affect the rate of reaction
The rate of reaction is greater in the concentrated solution because of the increased frequency of collisions between the hydrogen ions and the zinc. An increase of collisions results in a greater probability of successful collisions between the reactant particles and consequently an increase in the rate of reaction.
How does pressure affect the rate of reaction
Increasing the pressure for a reaction that involves gases means that there are more gas particles in a given volume, effectively increasing the concentration. This results in an increase in the frequency of collisions between reactant particles and an increase in the rate of reaction.
How does surface area affect the rate of reaction
Breaking up a solid into smaller pieces increases the surface area per unit volume and causes an increase in the rate of reaction.
What do catalyst do
Catalysts are used to increase the rates of chemical reactions. They achieve this by providing an alternative reaction pathway that has a lower activation energy than the uncatalysed pathway
