[dmk007]

Hey i'd appreciate if someone could help me with this, i think Kp is 2674.580 and Kc is 756.673

The following reaction occurs during the production of sulphuric acid
2SO2 + O2 - 2SO3

In this system at a given temperature, the initial conecentrations of sulphur dioxide, oxygen and sulphur trioxide were 8.5mol dm-3, 3.5mol dm-3 and 5.575mol dm-3. If at equilibrium, 0.075 moles of oxygen were left calcualte the concentrations of all the constituents at equilibrium. Then, calculate the equilibrium constant for the reaction. If the total pressure in the chamber was 4 atmospheres, calculate Kp for the reaction. 

[Astrokel]

Hey dmk007,

try to draw up an ICE table first


good luck!

[dmk007]

how do you do that?

[Astrokel]

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

Do you want us to check with the answer you stated or is that the actual answer?

[dmk007]

Check it if you can but I was given the answer with the question so it is probably right

[dmk007]

i still don't understand exactly what to do

[Astrokel]

Ok ICE table works this way,

                       2SO2 + O2  <---> 2SO3
[Intial]              8.5      3.5          5.575
[Change]           -2x      -x            +2x
[Equilibrium]      (8.5-x) (3.5-x)     (5.575+2x)

Do you understand how it works?

To calculate Kc, use the concentration at equilibrium, but you need to solve for x first.

As for Kp, it's the same, just that partial pressure is used this time.

And, the answer is correct.

[dmk007]

i get it now thanks very much Astrokel i'm repeating exams at the moment and your help is invaluable..