Kinetics Flashcards
How does a chemical reaction occur?
Chemical reactions occur when particles of substances collide. For a reaction to occur successfully, these collisions must have energy greater than or equal to the activation energy of the reaction.
What is the definition of activation energy?
The minimum amount of energy which particles need to collide to start a reaction.
What is the Maxwell-Boltzmann distribution?
Shows the spread of energies that molecules of a gas or liquid may have at a particular temperature.
Why should the energy distribution start at the origin?
The energy distribution should go through the origin as there are no molecules in the start with energy.
Why should the energy distribution never meet the x axis?
The energy distribution should never meet the x axis because there is no maximum energy for molecules.
What does the area under the curve represent?
The total number of particles present.
What is the reaction rate defined as?
The change of concentration of a substance in unit time
How is the rate measured?
Gradient of tangent to curve.
What is the initial rate?
The initial rate is at the start of the reaction where the reaction is the fastest.
How is the rate of reaction plotted?
The graph of concentration vs the time.
What is the effect of increasing pressure and concentration?
At higher concentrations and pressures, there are more particles per unit volume and so there particles collide with a higher frequency and there will be a higher frequency of effective collisions.
If the concentration increase what will happen to the shape of the graph?
The shape of the graph will not change however the the curve will be higher and the area under the curve will be greater as now there is an increase of particles.
What is the effect of increasing temperature?
At higher temperatures the energy of the particles increases. There will be more frequent collisions that have greater energy than the activation energy. More collisions result in a reaction.
What is the effect of surface area?
The effect of surface area will lead to more successful frequent collisions between the reactant particles that will increase the rate of reaction.
What is the definition of catalysts and what is their effect on the rate of reactions?
Catalysts increase the rate of reaction without getting used up. They provide an alternative energy or mechanism route with a lowers the activation energy.
