Parallel or Competitive Reactions
When a substance reacts simultaneously to give two different products, a parallel or competitive reaction is said to take place.
- Two first order reactions:
and, with constants and and rate equations, and
The integrated rate equations are then ; and .
One important relationship in this case is
- One first order and one second order reaction:
This can be the case when studying a bimolecular reaction and a simultaneous hydrolysis (which can be treated as pseudo order one) takes place: the hydrolysis complicates the study of the reaction kinetics, because some reactant is being "spent" in a parallel reaction. For example A reacts with R to give our product C, but meanwhile the hydrolysis reaction takes away an amount of A to give B, a byproduct: and . The rate equations are: and . Where is the pseudo first order constant.
The integrated rate equation for the main product is, which is equivalent to . Concentration of B is related to that of C through
The integrated equations were analytically obtained but during the process it was assumed that therefeore, previous equation for can only be used for low concentrations of compared to 0
Read more about this topic: Rate Equation
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