Module 3: Reaction rates Flashcards
What’s collision theory?
A reaction will not take place between 2 particles unless they collide in the correct orientation and collide with at least a certain minimum amount of kinetic energy (activation energy)
Define activation energy
The minimum energy required for a reaction to occur
What’s the rate of reaction defined as?
Rate of reaction = change in concentration / Time
What are the 4 factors that affect the rate of collisons?
- Concentration
- Pressure
- Surface area
- Temperature
How does increasing the concentration of reagents affect a solution?
It increases the number of reactant molecules in a given volume, so increases the frequency of collisions between molecules, therefore more frequent successful collisions.
How does increasing the pressure of a reactant affect the rate of reaction?
An increase in pressure means that there are more molecules in a given volume, therefore more frequent successful collisions.
How does increasing the surface area of affect the rate of reaction?
Increases the number of reactant molecules available for collision and so increases the frequency of successful collisions.
How does increasing the temperature effect the rate of reaction?
An increase in temperature always increases the rate of reaction. Molecules have more energy at higher temperatures. This leads more molecules with energy greater than the activation energy and therefore more frequent successful collisions
What is the basis of the maxwell boltzmann distribution?
The particles in a reaction undergo random collisions, in which energy is transferred between the colliding particles. As a result, there will be particles with different energies.
Draw the maxwell boltzmann distribution curve.
How does temperature effect the maxwell boltzmann distribution curve?
At higher temperature, many more particles have energy greater than Ea, therefore the rate of reaction is greater, as there are more frequent sucessful collisions. Curve is longer and there’s more area under the asymptote.
What is a catalyst?
A catalyst is a substance that increases the rate of reaction but itself is unchanged at the end of the reaction.
How does a catalyst work?
It provides an alternate route that has a lower activation energy.
What are heterogenous and homogenous catalysts?
Heterogenous - Catalysts which are in a different phase to the reactants.
Homogenous - Catalysts which are in the same phase as the reactants.
How are catalysts useful in the environment?
The use of catalysts in the industrial processes can be beneficial to the environment as they lower the energy demand for a reaction. Reaction can be done at lower temperatures and results in reduced CO2 emissions as less fossil fuels are being burned.
