Question

A.) The equilibrium constant for the reaction A(g) ⇌ B(g) is 10² . A reaction mixture initially contains [A] = 18.6 M and [B] = 0.0 M. Which statement is true at equilibrium?

	The reaction mixture contains [A] = 18.4 M and [B] = 0.2 M.
	The reaction mixture contains [A] = 0.2 M and [B] = 18.4 M.
	The reaction mixture contains [A] = 1.0 M and [B] = 17.6 M.
	The reaction mixture contains [A] = 9.30 M and [B] = 9.30 M.

B.) Determine the value of K_c for the following reaction if the equilibrium concentrations are as follows: [H₂]_eq = 0.14 M, [F ₂]_eq = 0.39 M, [HF]_eq = 1.6 M.

H₂(g) + F ₂(g) ↔ 2 HF(g)

	3.4 × 10-2
	29
	8.7 × 10-2
	47
	2.1 × 10-2

C.) The equilibrium constant is equal to 5.00 at 1300 K for the reaction:

2 SO₂(g) + O₂(g) ↔ 2 SO₃(g).

If initial concentrations are [SO₂] = 3.60 M, [O₂] = 0.45 M, and [SO₃] = 5.40 M, the system is

	not at equilibrium and will shift to the left to achieve an equilibrium state.
	not at equilibrium and will remain in an unequilibrated state.
	at equilibrium.
	not at equilibrium and will shift to the right to achieve an equilibrium state.

D.) The equilibrium constant, K _p, equals 3.40 for the isomerization reaction:

cis-2-butene ↔ trans-2-butene.
If a flask initially contains 0.250 atm of cis-2-butene and 0.165 atm of trans-2-butene, what is the equilibrium pressure of each gas?

	P(cis-2-butene) = 0.0458 atm and P(trans-2-butene) = 0.156 atm
	P(cis-2-butene) = 0.0735 atm and P(trans-2-butene) = 0.250 atm
	P(cis-2-butene) = 0.0485 atm and P(trans-2-butene) = 0.165 atm
	P(cis-2-butene) = 0.0943 atm and P(trans-2-butene) = 0.321 atm

E.) Consider the reaction SO₂(g) + NO₂(g) ↔ NO(g) + SO₃(g) at 460°C. What is the equilibrium concentration of the SO₃ if the initial concentrations are [SO₂] = [NO₂] = 3.00 x 10^-3 M and [NO] = [SO₃] = 4.00 x 10^-2 M? The value of the equilibrium constant for the reaction is 85.0 at 460°C.

	7.72 x 10-3 M
	8.15 x 10-2 M
	4.20 x 10-3 M
	1.80 x 10-3 M
	4.56 x 10-2 M
	3.88 x 10-2 M

Answer 1

A.)   A(g) ⇌ B(g)

Initial 18.6 M 0 M

At equilibrium 18.6 - x x M

Equilibrium const = x/(18.6 - X) = 102

x = 18.4

[B] = 18.4 M

[A] = 0.2 M

B.)   H₂(g) + F₂(g) ↔ 2 HF(g)

K_c = [HF]_eq²/[H₂][F₂]

= (1.6)²/(0.14)(0.39)

  K_c   = 46.9 = 47

C.)   2 SO2(g) + O2(g) ↔ 2 SO3(g).

above reaction equilibrium const for forward reaction is 5 and reverse reaction 1/5

forward reaction is more faster than reverse reaction

not at equilibrium and will shift to the right to achieve an equilibrium state.

D.)   cis-2-butene ↔ trans-2-butene   K_p = 3.4

initial 0.25 atm 0 atm

At equilibrium 0.25 - x atm x atm

K_p = x/(0.25 - x) = 3.4

x = 0.19 atm

  

trans-2-butene ↔ cis-2-butene K_p = 1/3.4 = 0.3

initial 0.165 atm 0 atm

ar equilibrium 0.165 - x atm x atm

  K_p = x/(0.165 - x) = 0.3

x = 0.04 atm

[cis-2-butene]_eq = 0.25 - 0.19 + 0.04

= 0.1 atm

  [trans-2-butene]_eq = 0.165 + 0.19 - 0.04

= 0.315 atm

E.)   

SO2(g) + NO2(g) ↔ NO(g) + SO3(g)

Initial 3*10^-3 M 3*10^-3​ M 0 M 0 M

At equilibrium 3*10^-3 - x  M 3*10^-3​ - x  M x M x M

K_c   = [NO][SO3]/[SO2][NO2] = 85

x²/(3*10^-3 - x)²  = 85

84x² - 510*10^-3 x + 765*10^-6 = 0

x = 2.196*10^-3 M

  

NO(g) + SO3(g) ↔ SO2(g) + NO2(g)

Initial 4*10^-2 M   4*10^-2​ M 0 M 0 M

At equilibrium 4*10^-2 - x  M 4*10^-2​ - x  M x M x M

K_c   = [SO2][NO2]/[NO][SO3] = 1/85

x²/(4*10^-2 - x)²  = 1/85

x = 3.91*10^{-3 M}

[SO3]_eq = 4*10^-2 + 2.196*10^-3 - 3.91*10^-3

   = 3.8*10^-2 m