[jpmiller89]

I'm in Chem 112 right now, and it's been a year since I've taken Chem 111.  I know the forum rules kind of frown upon asking questions without even starting the problem first, but I honestly don't know where to start

It goes like this:

A vessel is filled with NOBr to 0.762 atm and 65.1% decomposes.  Determine K_p for this reaction:

2NOBr(g) ::equil::2NO(g) + Br₂(g)

I tried doing the equilibrium equations and stuff like that, but I just don't know where to incorporate the percentage of decomposition within the whole picture :\

[jpmiller89]

I think I might know.

Like, what I did, was this:

(.762*.651)*2/3 for 2NO

And then the same for Br₂ but multiplied by 1/3 to get the atms.  Am I doing it right?

[Borek]

I am not sure why you are multiplying by 2/3.

Start with simple stoichiometry - you know how much decomposed, that is enough to calculate final moles of each substance at equilibrium. Knowing moles you can calculate final pressure (hint: vessel is closed, so V=const).