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=5.40 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=0.640 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

A)

2 COF2 --> C02 + CF4

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

using ICE table

at equilibrium

[C02] = y

[CF4] = y

[COF2] = 2 - 2y

so

5.4 = [y] [y] / ( 2-2y)^2

sqrt (5.4) = y / ( 2-2y)

2.32379 ( 2- 2y) = y

2 - 2y = 0.43033y

y = 0.823

so

at equilibrium

[CO2] = y = 0.823

[CF4] = y = 0.823

[COF2] = 2 - 2y = 2 - ( 2 x 0.823) = 0.354 M

so

0.354 M of COF2 remains at equilibrium

B)

using ICE table

at equilibrium

[CO] = 1 - y

[NH3] = 2 - y

[HCONH2] = y

now

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

0.64 = y / ( 1-y) (2-y)

0.64 ( 2-3y + y2) = y

1.28 - 1.92y + 0.64y2 = y

0.64y2 - 2.92y + 1.28 = 0

y = 0.49125

now

at equilibrium

[HCONH2] = y = 0.49125 M