Equilibrium Practice

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.

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]

Tags

NGSS.HS-PS1-6

NGSS.HS-PS1-7

SO₂Cl₂(g) ⇌ SO₂(g) + Cl₂(g)

Write the equilibrium constant expression in terms of concentrations

e

a

[SO₂]+[Cl₂]

[SO₂Cl₂]

[SO₂][Cl₂]

[SO₂]

[Cl₂]

Tags

NGSS.HS-PS1-5

CaCO₃(s)     ⇌    CaO(s) + CO₂(g)

Write the equilibrium constant expression in terms of concentrations

c

f

1

[CaO]+[CO₂]

[CaCO₃]

[CaO][CO₂]

[CO₂]

[CaO]

Co(s) + 2 H⁺(aq) ⇌ Co²⁺(aq) + H₂(g)

Write the equilibrium constant expression in terms of concentrations

f

c

[Co²⁺][H₂]

[H⁺]

[H₂]

[Co][H⁺]²

[Co²⁺]

[Co][H⁺]

[H⁺]²

[Co]

Tags

NGSS.HS-PS1-5

For the reaction below, calculate the equilibrium constant K_c if [HA]_eq = 1.65 x 10^–2 M and [H⁺]_eq = [A^–]_eq = 5.44 x 10^–4 M.

HA (aq) ⇌ H⁺ (aq) + A^– (aq)

Mathematical Equivalence

ON

If the value of the equilibrium constant is 1000, then at equilibrium, mostly _______ will be present

• catalysts

• reactants

• products

• intermediates