1.5 Kinetics Flashcards
What is collision theory?
For a successful collision to occur, the particles must collide with energy equal to or greater than the activation energy.
List factors that affect the rate of chemical reactions
- increasing the temp
- increasing the concentration of a solution
- increasing the pressure of a gas reaction
- increasing the surface area of solid reactants
- using a catalyst
Describe how increasing the temp, increases the ROR
It give the particles more kinetic energy, which increases their energy and number of collisions.
More particles have energy equal to or greater than the activation energy.
Describe how increasing the concentration of a solution, increases the ROR
If there are more particles present, in a given solution, then collisions are more likely and the reaction rate would be faster.
However as a reaction occurs, the concentration of reactants will decrease so ROR drops as the reaction goes on
Describe how increasing the surface area of solid reactants, increases ROR
The greater the total SA, the more of its particles are available to collide with molecules in gas or liquid. There are more sites for a reaction
Describe how using a catalyst increases the ROR
Provides alternative pathway to the reaction with a lower activation energy.
More particles have energy equal to or greater than the activation energy.
What is activation energy?
The minimum amount of energy required before a reaction can occur
What does the area under the curve in a maxwell-Boltzmann curve measure?
The total number of particles present
Important things to remember about MB distribution
- no particles have zero energy
- most particles have intermediate energy’s - around the peak of the curve
- a few have very high energies (there is no upper limit)
What does most probable energy stand for on a Maxwell-Boltzmann distribution?
The most probable energy that the system will have (mode)
What does average energy represent on maxwell-Boltzmann distribution?
The average energy of the particles in the system (mean)
Describe the effect of increasing temp will have on the Maxwell-Boltzmann distribution
- curve moves down and left
- a large increase in in the area after activation energy line: more particles have energy equal to or greater than the activation energy
Describe the effect of decreasing temp on the maxwell-Boltzmann distribution
- curve moves up and right
- smaller area after activation energy line as less particles have energy equal to or greater than the activation energy
What catalyst is used in the decomposition of hydrogen peroxide?
Manganese (IV) oxide, MnO2
What catalyst is used in the nitration of benzene
Concentrated sulphuric acid
