AP Unit 6 Review

Given the K_c for a forward reaction, how can you find K_c for the reverse reaction?

• Divide K_c by 1

• Divide 1 by K_c

• Square K_c

• Take the square root of K_c

When the rate of the forward reaction is equal to the rate of backward reaction, the system is said to be in

• Chemical Equilibrium
• Chemical Balance
• Stoichiometry
• Chemical Reaction

At what time (in seconds) is equilibrium established?

• 0 seconds

• 1 second

• 5 seconds

• 10 seconds

Why is equilibrium called a dynamic state?

• Chemists try to convert as much reactants as possible into products.
• The reactions at equilibrium continue to take place once equilibrium is established.
• The products of a forward reaction are favored, so equilibrium lies to the right.
• All chemical reactions are considered to be reversible under suitable conditions.

What is the K_c expression for this reaction?
   2 NO_(g)  +  O_2(g) ⇌  2 NO_2(g)

• K_c = [NO₂]² / [NO]² [O₂]
• K_c =  [NO]² [O₂] / [NO₂]²
• K_c = [NO]² [O₂] [NO₂]²
• K_c = [NO₂]² / [NO]² +  [O₂]

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

When the following reaction reached equilibrium,

SO_{2 (g)} + NO_{2 (g)} <=> SO_{3 (g)} + NO (g)

it was found to contain:

0.40 M SO₃ , and 0.30 M NO,

0.15 M NO₂ , and 0.20 M SO₂.

Calculate the equilibrium constant for this reaction.

• 4.0

• 0.42

• 0.25

• 1.0

Which is true for a system at equilibrium?

• Forward reaction rate is faster than the reverse and concentrations are equal

• Forward and reverse reaction rates are equal and concentrations are constant

• Forward and reverse reaction rates are equal and concentrations are equal

• Forward reaction rate is faster than the reverse and concentrations are constant

What is [H₂O] if K = 1.2,
[CO₂] = 0.846M, & [CH₄]= 0.0713M?
4CuO_(s)+CH_4(g)↔CO_2(g)+4Cu_(s) +2H₂O_(g)

• 0.101 M
• 0.318 M
• 0.0102 M
• 3.77 M

What is the correct equilibrium expression for the following reaction:

2H₂O₂ (aq) ↔ 2H₂O (l) + O₂ (g)

• [H₂O]²[O₂] / [H₂O₂]²

• [H₂O₂]² / [H₂O]²[O₂]

• [O₂] / [H₂O₂]²

• [H₂O]² / [H₂O₂]²