Question

Part A
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=5.60
If only COF2 is present initially at a concentration of 2.00 M, what concentration of COF2 remains at equilibrium?

Part B
Consider the reaction
CO(g)+NH3(g)⇌HCONH2(g), Kc=0.750
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?
Express your answer with the appropriate units.

Answer 1

let 2x= drop in concentration of COF2

at equilibrium CO2= x and CF4= x   COF2= 2-x

Kc for the reaction 2COF2 -----CO2+ CF4

Kc= [CO2] [F4]/ [COF2]2 = x²/ (2-2x)² = 5.6

x/(2-x)= 2.366

x= 2.366*(2-2x)

x= 2.366*2-4.672x

5.672x= 2.366*2

x= 0.8342

At equilibrium COF2 =2-2*0.8342 =0.3316

Part B

CO(g)+ NH3(g) ----HCONH2(g)

let x =drop in concentration

At Equilibrium CO =1-x   NH3= 2-x   and HCONH2=x

Kc= [HCONH2]/ { [CO] [NH3] }

x/ {(1-x)*(2-x)} = 0.75

x/(x²-3x+2)= 0.75

this can be solved by quadrtatic equation or alternatively, assuming some x and matching LHS and RHS. This is done in excel it give x= 0.37

At equilibrium [CONH2]=0.37M