Parallel irreversible first-order reactions are P→Q with k₁=0.05 min⁻¹ and P→R with k₂=0.15 min⁻¹. Initially only P is present at 4 mol/L. Find R concentration after 10 min in mol/L (two decimal places).
Total disappearance constant is k₁+k₂=0.20 min⁻¹, so $[P]=4e^{-0.20t}$. The fraction of consumed P that forms R is k₂/(k₁+k₂)=0.75. Therefore $[R]=0.75(4)(1-e^{-2})=2.594$ mol/L, or 2.59. Both pathways compete for the same decreasing reactant.
More Kinetics and Reaction Dynamics: Elementary, parallel, opposing, and consecutive reactions. Steady state approximation. Mechanism of complex reactions. Unimolecular reactions. Potential energy surface and classical trajectories, Concept of saddle points, Transition state theory: Eyring equation, thermodynamic aspects. Kinetics of polymerization. Catalysis concepts and enzyme catalysis. Kinetic isotope effects. Fast reaction kinetics: relaxation and flow methods. Diffusion controlled reactions. Kinetics of unimolecular and bimolecular photophysical processes, Quantum yield calculation, static and dynamic quenching. questions
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