We have the reaction:
1. H2+ICl-HI + HCl (slow step)
2. HI + ICl- I2+HCl (fast step)
summarising:
H2+2ICl -I2 + 2 HCl

a) Which step is rate-determing and why?
b) Write the reaction rate ( the answer is v=k[H2][ICl] and why it is not [ICl]^2? )

Question

We have the reaction:
1. H2+ICl->HI + HCl (slow step)
2. HI + ICl-> I2+HCl (fast step)
 summarising:
H2+2ICl ->I2 + 2 HCl

a) Which step is rate-determing and why?
b) Write the reaction rate ( the answer is v=k[H2][ICl] and why it is not [ICl]^2? )

jfraser · Answer

can a reaction occur faster than the slowest step of the reaction allows it to be?

anonymous · Answer

Thank you. And can you tell me why I can't do [ICl] squared?

jfraser · Answer

the rate law will be determined by the rate determining step. the rate determining step is first order in $H_2$ and first order in $ICl$.