MHT CET202525 Apr 2025Evening ShiftChemistryChemical KineticsActual
Which of the following is an example of second order reaction?
Options
- A2 H ₂ O _ 2( ~g ) 2 H ₂ O _ ( ) + O _ 2( ~g )
- BH _ 2( ~g ) + I _ 2( ~g ) 2 HI _ ( g )
- CCH ₃ CHO _ ( g ) CH _ 4( ~g ) + CO _ ( g )
- D2 NO _ ( g ) +2 H _ 2( ~g ) N _ 2( ~g ) +2 H ₂ O _ ( g )
Correct answer
B. H _ 2( ~g ) + I _ 2( ~g ) 2 HI _ ( g )
Step-by-step solution
The reaction order is determined by the experimental rate law, not by the stoichiometric coefficients. Analyzing each option: A: 2 H ₂ O _ 2( g ) 2 H ₂ O _ ( ) + O _ 2( g ) . The gas-phase decomposition follows a first-order rate law: rate = k[ H ₂ O ₂] , with overall order 1. B: H _ 2( g ) + I _ 2( g ) 2 HI _ ( g ) . This bimolecular reaction has the rate law rate = k[ H ₂][ I ₂] , giving an overall order of 2. C: CH ₃ CHO _ ( g ) CH _ 4( g ) + CO _ ( g ) . The decomposition exhibits a fractional order: rate = k[