A <---> 2B + C

Question

at a certain temperature the equilibrium pressure of the system is 0.318atm. Determine Kp for this reaction.
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2B + C = 0.318atm /3 = 0.106
CO2 = 0.106 atm
NH3 = 2(1.06) atm =0.212 atm

Kp = PNH3 ^2 x PCO2
kp = 0.212^2 x 0,106

is that how this question is done?

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For % completion, how do you do it for this question?

Consider the rxn; 4A + B <---> 3C. Initially we had 12 mol of A 12 mol of B in a 2.00L flask, At equilibrium, there is 7.5mol of C in the flask.

Find K and % completion?

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I've got K and all the mols at equilibrium when i set up an ice chart for it to go right to equilibrium it goes like this:

4A + B ---> 3C
||4A|B|3C
I| 6 6 0
C|
E|

What must i do to get the %completion because i don't know which is the limiting reactant. thanks!

Answer 1

Can't you calculate the limiting reagent.
Starting with 6 mols B, how many mols A would you need for 100% reaction? That would be 6 mols B x (4 mols A/1 mol B) = 24 mols A and you don't have that much A; therefore, A must be the limiting reagent. Just to check that, how much B would you need for 100% reaction. That would be
6 mols A x (1 mol B/4 mols A) = 1.5 mols B and you have that much (which just proves A is the limiting reagent). Looks to me like you started with 12 mols and ended up with 2 mols (using 10 mols).