[Omslice_King_of_Persia]

I need Help on the following 3 problems
If you could show me each step that would be great

1)The decomposition of NO₂(g) occurs by the following bimolecular elementary reaction:  2NO₂->2NO(g)+O₂(g)
The rate constant at 273K is 2.3*10^-12 L/mole-sec.  The activation energy is 111kj/mole.  How long will it take for the concentration of NO2(g) to decrease from an initial partial pressure of 2.5 atm to 1.5 atm at 500K?  Assume ideal gas behavior.

2)Sulfuryl chloride undergoes first-order decomposition at 320 degrees C with a half-life of 8.75 hours.  What is the value of the rate constant, k , in sec^-1?  If the initial pressure of SO₂CL₂ is 791 torr and the decompostition occurs in a 1.25 L container, how many molecules of SO₂CL₂ remain after 12.5 hours? SO₂Cl₂(g) -> SO₂(g)+ Cl₂(g)

3)The decomposition of idoethane in the gas phase proceeds according to the following rxn: C₂H₅I(g)->C₂H₄(g)+HI(g).  At 660K, k=7.2*10^-4 sec^-1 and at 720.K, k=1.7*10^-2 sec^-1.  What is the rate constant for this first-order decomposition at 325 degrees C?  if the initial pressure of iodoethane is 894 torr at 245 degrees celcius, what is the pressure of iodoethane after three half lives.

[Borek]

You just don't ask. You try, you tell us what you did, we push you in the right direction.

[Omslice_King_of_Persia]

Umm.. that's the problem. I have no clue how to do these. In my class the teacher calls these challenge problems. They are extremely hard for us and she made them above our level so that we have to go out and do research but I can't find out how to do them. She gives us the answers to the questions but that's not important to me. I would like to know what are my steps to get that answer. I have no clue how to approach the problem. Our teacher told us that PV=nRT will help you, but I have no clue how that helps out.

[cliverlong]

For your first question.
Entering "rate constant" in Google turned up this as the first response in the list

http://en.wikipedia.org/wiki/Rate_constant

Scanning through the entry I see the terms

"activation energy"
 "gas constant"
and the unit for rate coefficient is "mol L^-1 s^-1"
These terms appear in your question.

Perhaps there are other entries in the list that Google returns on the first page that will give you the background and even worked examples for you to consider.

Clive

[Omslice_King_of_Persia]

I am still not getting this at all. I am sorry I am really stupid. I guess I forgot to mention that.

[cliverlong]

Try this:
http://www.chemguide.co.uk/physical/basicrates/arrhenius.html#top

and if that is too advanced, start here:
http://www.chemguide.co.uk/physical/basicratesmenu.html#top
and work through all the topics

I am still not getting this at all. I am sorry I am really stupid. I guess I forgot to mention that.

That is indeed is a handicap and will impede your progress.

Clive

[Omslice_King_of_Persia]

so then i do?


2.3*10^-12L/mole-sec=Ae^{111000/(8.314)(500K)}

and Ae = 2.9037?