Chemical Reaction: Rate/Velocity, Types of Rates, Relation between Reaction Rates
Rate/Velocity of chemical reaction
The rate of change of concentration with time of different chemical species taking part in a chemical reaction is known as rate of reaction of that species.
Rate is always defined in such a manner so that it is always a positive quantity.
Types of Rates of chemical reaction
For a reaction R à P
Average rate = Total change in concentration / Total time Taken
Instantaneous Rate: Rate of reaction at a particular instant.
Instantaneous rate can be determined by drawing a tangent at time t on curve drawn for concentration versus time.
Initial Rate: Instantaneous rate ‘t = 0’ is called initial rate [slope of tangent at t = 0]
Relation between reaction rates of different species involved is a reaction
These rates are not equal. Therefore, by convention the rate of a reaction is defined as
Note: Rate of reaction value is dependent on the stoichiometric coefficients used in the reaction while rate of any species will be fixed value under given conditions.