OZ.4 Flashcards
Measuring rates of reactions and the effect of temperature on reaction rate
What measures do you need to determine the rate of a reaction?
You need a measure of a property that changes during the reaction that is proportional to the concentration of a particular reactant or product.
What is the equation you can use to calculate rate of reaction?
Rate of reaction = change in property / time taken
What are five different ways you can measure property change of a reaction for calculating rate of reaction?
- Measuring the volume of gas produced.
- Measuring the mass change.
- Measuring the change in pH.
- Measuring the change in colour using a colorimeter.
- Chemical analysis.
What are the five factors that can affect the rate of a chemical reaction?
- The concentration of the reactants, or pressure in gases.
- The temperature.
- The intensity of radiation with reactions that involve radiation.
- The size of particles with reactions with solid reactants.
- The presence of a catalyst.
How does the collision theory explain how reactions happen?
The collision theory it’s the idea that reactions occur when particles of reactants collide with a certain minimum kinetic energy.
According to the collision theory why does increasing the concentration of reactants increase the rate of reaction?
A higher concentration of reactants means that there are more particles of reactants in a given volume, and therefore they’re more likely to collide, and will collide more frequently, increasing the rate of reaction.
Does every collision cause a reaction?
No, because only the particles that collide with a sufficient amount of energy on collision to overcome the energy barrier can react and go on to produce products.
What is activation enthalpy?
The minimum amount of energy the particles will need on collision to overcome the energy barrier of bond breaking or forming in order for a reaction to happen.
According to the collision theory why doses increasing temperature increase the rate of reaction?
At higher temperatures, more particles will have enough energy to overcome the activation enthalpy and react on collision.
What is the transition state of a reaction?
The point where old bonds stretch and new bonds start to form.
How does the presence of a catalyst increse the rate of a reaction?
Catalyst provides an alternative reaction pathway that has a lower activation enthalpy therefore more particles will have enough energy to react and so rate increases.
What is the Maxwell-Boltzmann curve used to show?
It shows the distribution of particles’ kinetic energies at a given temperature.
