07 Reaction Kinetics Flashcards
Rate of reaction
Change in concentration of a particular reactant or product per unit time
Instantaneous rate
Rate at a particular time (any time specified)
Average rate
Rate during a specific time interval
- gradient of line drawn between 2 points
Initial rate
Rate when t=0
Rate equation
Mathematical expression that relates the rate of a reaction to the concentration of reactants raised to the appropriate powers
Rate constant
Constant of proportionality, k in the rate equation at a given temperature
Order of reaction with respect to a reactant
Is the power to which the concentration of that reactant is raised in teh rate equation
Overall rate of reaction
Sum of the powers of the concentration terms in rate equation
Half-life of a reaction
Time taken for concentration of a reactant to fall to half its initial value
Intermediate
Species formed in one step and consumed in the subsequent step
Rate-determining step
Slowest step in the reaction mechanism
- determines overall rate of reaction
Collision theory (3 statements)
- Reactant particles must collide to react
- Reactant particles must collide in favourable orientation in order to react
- React particles must collide with certain minimum amount of energy (activation energy) in order to react
What is activation energy ?
Minimum amount of energy that the reactant particles must possess before they can collide to result in a reaction
What is a catalyst
substance which increases rate of reaction without itself undergoing any permanent chemical change
- provides alternative reaction pathway of lower Ea
What are homogenous catalysts
In the same physical state as the reactant particles
