Kinetics Flashcards
Define rate of a reaction
the change in concentration of reactants (or products) per unit time
Define activation energy
the minimum energy required for a collision to be successful
Explain the collision theory
For a reaction to take place between two particles , they must collide with enough energy to break bonds = the particles must possess a minimum amount of energy equal to the activation energy
the particles must collide with favourable spatial orientation = the collision needs to take place between the parts of the molecule that are going to react together
Why is increasing the rate of chemical reactions important in industry?
more product can be produced in a given time = helps to reduce cost
How can the rate of chemical reactions be calculated?
measuring the rate at which the products are formed or the rate at which the reactants are used
State and explain the factors that affect the rate of chemical reactions
- increasing the temperature - increases the Ke of particles = increases speed = collide with more energy and increases number of collisions in a given time
- Increasing the concentration of a solution - more particles present in a given volume = collision more likely = rate of reaction faster
- increasing pressure of a gas reaction- same effect as concentration. Also particles are further apart
- increasing the surface are of solid reactants - more reactant particles are exposed to the other reactant = increase number of collisions per given time
- using a catalyst
Describe the heat energy transfer in EXOTHERMIC reactions. Describe and draw energy profile
transfers heat energy from the chemicals to the surroundings
The energy of products is less than the energy of reactants because energy has been lost to surroundings in the form of heat. SEE GRAPH
Describe the heat energy transfer in ENDOTHERMIC reactions. Describe and draw energy profile
takes in energy from the surroundings
The energy of products is greater than the energy of reactants as energy has been absorbed from the surroundings.
What does the Maxwell-Boltzmann distribution show?
shows the distribution of molecular energies in a gas
Label the Maxwell-Boltzmann distribution (including the average energy and most probable energy)
What happens to the Maxwell-Boltzmann distribution when there is an increase in temperature?
the peak becomes lower and shifts to the right
asymptote is higher
What happens when you add a catalyst?
lowers activation energy by providing an alternative route = more particles with the greater energy than the activation energy = more successful collisions in a given time
What are inhibitors?
catalysts that reduce the rate of reaction
What is a catalyst?
a substance that increases the rate of a chemical reaction without being changed in chemical composition or amount
Why does the Maxwell- Boltzamann distribution have an asymtope
because there is a small probability that particles will have a very high energy
