Topic 16 Kinetics 2 Flashcards
What is reaction rate?
This is the measure of how fast a reaction takes place. This is calculated as the change in concentration of a reactant/product over unit time.
What collision theory?
For particles to react they must collide with sufficient energy at the correct orientation.
What is activation energy?
The minimum energy required to react.
What is the Maxwell-Boltzmann distribution?
This is a graph that displays the number of particles (y axis) against energy (x axis). Activation energy (Ea) is also displayed on the graph to allow the number of particles with the Ea to be calculated.
What factors effect rate?
Concentration –> Increased conc = particles are closer together ∴ there are more frequent successful collisions.
Surface area –> Increased surface area = more particles able to react ∴ there are more frequent successful collisions.
Pressure –> Increased pressure = particles are closer together ∴ there are more frequent successful collisions.
Temperature –> Increased temp = particles have a higher kinetic energy ∴ there are more frequent successful collisions.
Catalyst –> Use of a catalyst = Ea is reduced so more particles reach the Ea ∴ there are more frequent successful collisions.
How can you calculate the rate of reaction using gradients?
On a graph displaying the change in factor (e.g. concentration) / time, calculating the gradient at a specific point (by drawing a tangent) will display the rate of the reaction at that point.
This can be done at multiple points to display the change in rate of reaction.
What effects do zero, first and second orders have?
Zero - The reaction rate is proportional to [A]ᵒ (=1) and therefore the rate is not effected by any changes
First - The rate of reaction is proportional to [A]
Second - The rate of reaction is proportional to [A]²
What is the rate equation and rate constant?
Equation - Rate = K[A]ᵐ[B]ⁿ (where [A] & [B] represent the concentration of the reactants in moldm⁻³)
Constant - K
What is the Arrhenius equation?
K = Ae⁻ ᴱᵃ/ᴿᵀ / ln K = ln A - Eₐ/RT
How can activation energy be calculated?
By rearranging ln K = ln A - Eₐ/RT
This is done by
Eₐ/RT = ln A - ln K
Eₐ = RT(ln A - ln K)
What is the half-life of a reaction?
The time for the concentration of one of the reactants to fall by half.
What are reaction orders and the overall order of a reaction?
Reaction orders - The powers m and n in K[A]ᵐ[B]ⁿ
Overall order of reaction - The sum of all orders for all substances that appear in the rate equation.
∴ m + n in K[A]ᵐ[B]ⁿ
What is the mechanism of a reaction?
How the reaction takes place, displaying step by step the bonds that break and the new bonds that form.
What is adsorption?
A process in which the atoms, molecules or ions are held on the surface of a solid.
What is the rate-determining step?
In a multi-step reaction, this is the slowest step / the step with the highest activation energy.
