Posted by David on .
Arrows disappeared from below added them back to the equations.
??(a) I don't understand ln(No/N)=akt
Is (a) 3.77
The decomposition of IBr(g)into I2 (g) and Br2 (g) is first order in IBr with k = 0.00255/sec.
(a)Starting with [IBr] = 1.50M, what will [IBr] become after 2.50 minutes?
(b)How long, in minutes, will it take for [IBr] to go from 0.500M to 0.100M?
(c)What is the halflife for this reaction in seconds?
(d)Enough IBr is added to an evacuated container to make [IBr] = 0.350M. How long will it take [I2] = 0.100M?
(e) The following mechanism has been proposed for the reaction above:
(step 1)IBr (g) > I (g) + Br (g)(step 2)IBr(g)+ Br(g) > Br2(g)+ I (g)(step 3)I(g) + I (g) > I2 (g)
Based on the rate law described above, which step is the ratedetermining step? ______________
What is the molecularity of the ratedetermining step? _____________________

ChemistryDrBob222 
DrBob222,
I don't know the problem so I don't know what the answer to a is. For the ln(No/N) = akt problem see below.
You know k = 0.00255/sec
2IBr ==> I2 + Br2
ln(No/N) = akt
No = 1.50M from the problem. That's what you start with.
N = The M at time t.
a is the coefficient 2 for IBr.
k is from above.
t = 2.5 minutes from the problem but since k is in seconds (I assume the half life given is in seconds) then you must convert 2.5 minutes to seconds. Solve for N to determine the M at time 2.5 minutes.