I've been stuck with this problem:
The following reaction has Kc = 2.8 · 102
at T=1000 K:
A reactor with volume V = 10 L initially contains 0.32 mol C2
, 0.16 mol H2
and 0.68 mol C2
Calculate the number of C2
a) the addition of 1.00 mol of C2
in the reactor.
b) the volume of the reactor is increased by 20 L.
I know the answer to a) must be 1.515 moles, while b) must be 0.645 moles.
I can see these numbers make sense by LeChatelier principle. By adding 1 mole to 0.68 mol you get 1.68 mol of C2
, but a part of it gets converted back to its reactants; by adding 20 L to the volume of the recipient, you shift the equilibrium position towards the reactants (because they are gaseous, so they are entropically favoured)
I tried to solve this exercise with ICE tables, resulting in
Numerator: 1.68 + x
Denominator: (0.32 - x) × (0.16 -x)
But when I solve for Numerator/Denominator = Kc, I do not get the answers above. I also do not know how to include volume in my calculation. I've tried using the ideal gas law and converting into partial pressures, but I still do not get the correct answer.