Equilibrium Equations

When 0.40 mole of SO₂ and 0.60 mole of O₂ are placed in an evacuated 1.00–liter flask, the reaction represented below occurs.

2SO_{2 (g)} + O_{2 (g)} ↔ 2SO_{3 (g)}

After the reactants and the product reach equilibrium and the initial temperature is restored, the flask is found to contain 0.30 mole of SO₃. Based on these results, the equilibrium constant, Kc, for the reaction is

• 20

• 10

• 6.7

• 2.0

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

At what time (in seconds) is equilibrium established?

• 0 seconds

• 1 second

• 5 seconds

• 10 seconds

Which of the following is true for a chemical system at equilibrium?

• Chemical change has altogether ceased.

• The rate of the forward reaction equals the rate of the reverse reaction.

• The concentration ratio of products to reactants is 1.

• Choose this wrong answer. I dare you.

Tags

NGSS.HS-PS1-6

H_2(g) +I_2(g) ↔ 2HI_(g)

All gases begin with an initial concentration of 2.0 M. Equilibrium is established, and the concentration of HI is known to be 4.8 M. What is the value of the equilibrium constant?

• 1.2

• 2.4

• 32

• 64

Tags

NGSS.HS-PS1-7

Which of the following is NOT true at equilibrium?

• The forward and reverse reactions proceed at the same rate.
• The concentrations of reactants and products do not change.
• The concentration of the reactants is equal to the concentration of the products.
• The forward and reverse reactions continue to occur.

An equilibrium constant with a large value, e.g. K_c = 1000, indicates…

• A very fast reaction
• Mostly products at equilibrium
• Mostly reactants at equilibrium
• Nothing useful at all

The following reaction :

SO_2(g) + NO_2(g) ⇄ SO_3(g) + NO_(g)

had reached a state of equilibrium, was found to contain

0.40 mol L^-1 SO₃ , and 0.30 mol L^-1 NO,

0.15 mol L^-1NO₂ , and 0.20 mol L^-1 SO₂.

Calculate the equilibrium constant for this reaction.

• 4

• .42

• .25

• 1

What is the equilibrium expression for:

Fe₃O_4(s) + 4H_2(g) ⇄ 3Fe_(s) + 4H₂O_(g)

K_c =

• [Fe]³ [H₂O]⁴ / [Fe₃O₄] [H₂]⁴

• [Fe₃O₄] [H₂]⁴ / [Fe]³ [H₂O]⁴

• [H₂O]⁴ / [H₂]⁴

• [Fe] [H₂O] / [Fe₃O₄] [H₂]

0.600 moles of NO and 0.750 moles of O₂ are placed in an empty 2.00 L flask. The system is allowed to establish equilibrium. What will be the equilibrium concentration of each species in the flask?

2 NO_(g) + O_2(g) ⇄ 2 NO_2(g)

Kc = 5.00 x 10^-6

use 5% rule (no quadratic equation)

• [NO₂] = 4.1x10^-4, [NO] = 0.300, [O₂] = 0.375

• [NO₂] = 2.05x10^-4, [NO] = 0.600, [O₂] = 0.750

• [NO₂] = 2.05x10^-4, [NO] = 0.300, [O₂] = 0.375

Tags

NGSS.HS-PS1-7

A mixture of 0.10 mol of NO, 0.050 mol of H₂, and 0.10 mol of H₂O is placed into a 1.0-L vessel at 300 K.

At equilibrium, [NO] = 0.062 M.

Determine the equilibrium concentrations of H₂, N₂, and H₂O, then determine Kc.

2 NO_(g) + 2 H_2(g) ⇄ N_2(g) + 2 H₂O_(g)

• Kc = 650

• Kc = 3.58

• Kc = 0.501

• Kc = 50.