chem 1 question?

Question

I have:
hydrogen .5atm
iodine 1atm
hydrogen iodide 5.2 atm
in a 1 Liter container at 273 degrees K

I need to find the equilibrium constant:
in order to do that..i have to find the number of moles of each gas, but i'm not sure how to do that...using PV=nrT on each gas doesnt seem to give the right answer because 1 liter is my COMBINED volume ..not the volume of each gas...HELP!

How do i find the moles of each gas so that i can plug it into the formula for the constant?

Answer 1

You are quite right that 1 L is the combined volume, but believe it or not that doesn't matter Each separate gas spreads itself out over the complete volume. So for each gas, you can use the gas law equation with the same volume, in this case 1 L.

What does happen then is that each gas exerts pressure on the walls of the vessel, so that the total pressure is the sum of the partial pressures.