Question

Carbonyl fluoride, COF2, is an important intermediate used in the production of fluorine-containing compounds. For instance, it is used to make the refrigerant carbon tetrafluoride, CF4 via the reaction

2COF2(g)⇌CO2(g)+CF4(g),    Kc=6.80

If only COF2 is present initially at a concentration of 2.00 M, what concentration of COF2 remains at equilibrium?

Answer 1

consider the given reaction

2 COF2 ---> C02 + CF4

now

using the ICE table

initial conc of COF2 , CO2 ,CF4 are 2 , 0 , 0

change in conc of COF2 , CO2 ,CF4 is -2x , + x , + x

equilibrium conc of COF2 ,CO2 , CF4 are 2-2x , x , x

now

Kc = [C02] [CF4] / [COF2]^2

so

6.8 = [x] [x] / [ 2-2x]^2

6.8 = ( x / 2-2x)^2

x / (2-2x) = sqrt ( 6.8) = 2.607681

(2-2x) / x = 0.38348

(2/x ) - 2 = 0.38348

x = 0.839

now

at equilibrium

[COF2] = 2- 2x = 2 - 2 * 0.839 = 0.322

so

0.322 M of COF2 will remain at equilibrium