Carbonyl fluoride, COF2, is an important intermediate used in the production of
ID: 964211 • Letter: C
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=6.30
If only COF2 is present initially at a concentration of 2.00 M, what concentration of COF2 remains at equilibrium?
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Consider the reaction
CO(g)+NH3(g)?HCONH2(g), Kc=0.900
If a reaction vessel initially contains only CO and NH3 at concentrations of 1.00 M and 2.00 M, respectively, what will the concentration of HCONH2 be at equilibrium?
Explanation / Answer
Part A - Kc for the reaction,
Kc = [CO2][CF4]/[COF2]^2
with,
[COF2] = 2.0 M
and asuming x be the change in concentration at equilibrium
we get,
6.30 = x^2/(2 - 2x)^2
25.2 - 25.2x + 25.2x^2 = x^2
24.2x^2 - 50.4x + 25.2 = 0
x = 0.834 M
So at equilibrium the concentration for,
[COF2] = 2 - 2 x 0.834 = 0.332 M
Part B - Kc for the reaction,
Kc = [HCONH2]/[CO][NH3]
let x be the change in concentration at equilibrium,
0.9 = x/(1 - x)(2 - x)
1.8 - 2.7x + 0.9x^2 = x
0.9x^2 - 3.7x + 1.8 = 0
x = 0.564 M
So the equilibrium concentration of,
[HCONH2] = 0.564 M