NEET2007ChemistryChemical KineticsActual
The reaction of hydrogen and iodine monochloride is given as: H _ 2(g) +2 ICl _ (g) 2 HCl _ (g) + I _ 2(g) This reaction is of first order with respect to H _ 2(g) and lCl _ (g)+ following mechanisms were proposed Mechanism A: H _ 2(g) +2 ICl _ (g) 2 HCl _ (g) + H _ 2(g) Mechanism B: aligned & H _ 2(g) + ICl _ (g) HCl _ (g) + HI _ (g) :slow & Hl _ (g) + lCl _ (g) HCl _ (g) + l _ 2(g) ; fast aligned Which of the above
Options
- AA and B both
- Bneither A nor B
- CA only
- DB only
Correct answer
A. A and B both
Step-by-step solution
The slowest step is the rate determining step thus the mechanism B will be more consistent because it involve one molecule of H ₂ and one molecule of ICl. It can be expressed as r=k [ H ₂ ][ ICl ] Related Theory The rate determining step in a reaction mechanism is characterised by high activation energy. Usually, the first step is the slow step since it has the highest activation energy.